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Cloning
Cloning is a feature that allows a sprite to create a clone, or semi-duplicate, of itself
Useful in tower defense games, for example, for a wave of objects.
Clones of a sprite will be the same as the original, or parent sprite, but as a separate instance.
Clones inherit the parent’s scripts, costumes, sounds, and properties, but can then be modified.
Limit of 300 clones per project to prevent lagging/crashes.
Main tutorial https://wiki.scratch.mit.edu/wiki/Clone
The Create Clone of () block is a control block and a stack block.
It creates a clone of the sprite in the argument. It can also clone the sprite it is running in, creating clones of clones, recursively.
Tutorial https://wiki.scratch.mit.edu/wiki/Create_Clone_of_()_(block)
When I Start as a Clone (block) – a control block and a Hat block.
It activates in a clone when it gets created.
It is the only Hat block in the Control palette; all the others are in Events, Motor, or PicoBoard.
Tutorial https://wiki.scratch.mit.edu/wiki/When_I_Start_as_a_Clone
Delete This Clone
Tutorial https://wiki.scratch.mit.edu/wiki/Delete_This_Clone
Duplicating Sprites: This is NOT the same as cloning

Critical thinking assignment
Being a science writer is harder than being a sports writer because sports writers don’t have to deal with people who think that basketball doesn’t even exist.
The nature of science. Students will work in a pair to research and answer one of the following questions:
a) Is the Earth flat (2D) or spherical? (3D)
what arguments did people make for the Earth being flat? what evidence did they bring forth? what arguments did people make for the Earth being spherical? and what evidence did they bring forth? Evidence is just a set of facts – we can’t draw conclusions unless we make logical connections between them. Explain their reasoning (how people reached their conclusion.)
You will need to look up additional resources in our school library, the city library, or on the internet. Here are 2 sources to help you get started. Within these sources you can find other sources to cite.
http://www.popsci.com/10-ways-you-can-prove-earth-is-round
https://kaiserscience.wordpress.com/physics/gravity/prove-that-the-earth-is-a-sphere/
b) Is the Earth thousands of years old, or billions of years old?
points to address: what arguments did people make for the Earth being thousands of years old? what evidence did they present? what arguments did people make for the Earth being billions of years old? what evidence did they present? Evidence is just a set of facts – we can’t draw conclusions unless we make logical connections between them. Explain their reasoning (how people reached their conclusion.)
You will need to look up additional resources in our school library, the city library, or on the internet. Here are 2 sources to help you get started. Within these sources you can find other sources to cite.
Half life of atoms: Using radioactive decay like a clock
https://phet.colorado.edu/en/simulation/radioactive-dating-game
http://www.talkorigins.org/faqs/dating.html
c) Is the Earth the center of our solar system, or is the Sun?
points to address: what is a star? what is a planet? what arguments did people make for the Earth being the center of our solar system? what evidence did they present? what arguments did people make for the our Sun being the center of our solar system – and what evidence did they present? Evidence is just a set of facts – we can’t draw conclusions unless we make logical connections between them. Explain their reasoning (how people reached their conclusion.)
You will need to look up additional resources in our school library, the city library, or on the internet. Here are 3 sources to help you get started. Within these sources you can find other sources to cite.
https://kaiserscience.wordpress.com/earth-science/astronomy/early-views-of-the-solar-system/
https://kaiserscience.wordpress.com/earth-science/astronomy/solar-system-the-modern-view/

d) Are all elements stable, forever, or do some atoms change into other others?
points to address: what is an “element”? How do elements differ from each other? Where do elements originally come from? How specifically did we discover that some elements change: what evidence did they have? Evidence is just a set of facts – we can’t draw conclusions unless we make logical connections between them. Explain their reasoning (how people reached their conclusion.)
First you need to be sure that you know what atoms and elements are! (These introductory websites don’t count as sources for your paper)
http://www.chem4kids.com/files/elem_intro.html
What is an Atom -Basics for Kids
Bill Nye The Science Guy – S05E08 – Atoms
Nuclear chemistry (KaiserScience)
You will need to look up additional resources in our school library, the city library, or on the internet. Here are 2 sources to help you get started. Within these sources you can find other sources to cite.
https://kaiserscience.wordpress.com/physics/modern-physics/nuclear-physics-and-radioactivity/
Half life of atoms: Using radioactive decay like a clock
https://phet.colorado.edu/en/simulation/radioactive-dating-game
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Writing your paper
It will be: typed, spell-checked, grammar-checked, doubled spaced, 12 point font, 1″ margins. No cover page. The upper left of the 1st page will include the name of you and your partner, my name, your block, and a title. The paper will be 5 pages long.
Part I – on science in general
1. Explain the difference between a claim that is, and isn’t, peer-reviewed
Peer review: 2 articles, with infographics
Scrutinizing science: Peer review
In search of quality: The scientific peer review process
2. Explain the difference between Fact, Opinion, Belief, and Prejudice
https://kaiserscience.wordpress.com/biology-the-living-environment/evolution/
3. Science answer questions about things that are “natural” – what does this mean? Science also has limits: What are topics that science doesn’t answer a question about?
http://undsci.berkeley.edu/article/0_0_0/natural
http://undsci.berkeley.edu/article/0_0_0/whatisscience_12
Part II – on your chosen topic.
4. Obtain 5 science-based sources on your topic. Cite the sources using MLA standards.
5. Summarize what science has learned on your topic.
6. Don’t just list measurements or facts. Explain how the data leads to the conclusion. Look at the grading rubric to see what is expected. Paper will be handed in on time by 1/23/17. Worth 100 points. Lose 5 points/day for late papers, including weekends and holidays. Grading rubric
Learning Standards
2016 Massachusetts Science and Technology/Engineering Standards
Students will be able to:
Nuclear fusion
nuclear fusion
https://kaiserscience.wordpress.com/physics/modern-physics/quantum-mechanics/
https://kaiserscience.wordpress.com/physics/modern-physics/nuclear-physics-and-radioactivity/
Barns Are Painted Red Because of the Physics of Dying Stars
External links
It’s Not Cold Fusion… But It’s Something – Scientific American
Low Energy Nuclear Reactions Work And Could Supplant Fossil Fuels – Edge.Org
Can Cold Fusion Come Back From the Dead? – Popular Mechanics
Elastic and Inelastic collisions
This lesson assumes that you have already learned about momentum and the difference between kinetic energy and potential energy.
When two (or more) objects collide, what determines their subsequent behavior? What happens next? The result will depend on whether they collide in an elastic or inelastic fashion. (or, more often, in a partially elastic fashion.)
Let’s take a look at these different kinds of collisions with some short animation clips (GIFs.) We’ll figure out the basic principles.
Elastic collisions
Objects collide:
(a) without being deformed
(b) no kinetic energy (energy of motion) is lost
Example 1: Gas molecules bouncing off of each other
Example 2 Pool (pocket billiards )

Example 3 car bouncing off of a truck
Example 4: Two cars colliding, without any (apparent) deformation or heating

Inelastic Collisions
Objects collide:
(a) and parts are deformed
(b) much kinetic energy (energy of motion) is lost, and turned into heat
Example 5: car hitting a truck, and they stick together
Example 6: car hitting a truck, and they stick together

Partially elastic collisions
Objects collide:
(a) and are slightly deformed
(b) some kinetic energy (energy of motion) is lost, and turned into heat
Example 7: Cars bounce after a collision

How can we tell if a collision is elastic or not?
.
How can we tell if a collision is elastic or not?
Take into account the kinetic energy (the energy of motion)
KE tr = KE translational
= kinetic energy as stuff “translates”, or moves
Video GIFs from http://waiferx.blogspot.com/2011/10/physics-presentation-collisions.html
Collisions in two dimensions
Conservation of momentum in two dimensions:

image from physicsclassroom
How can this kind of analysis be useful? In forensic accident reconstruction.

“Accident Reconstruction is the forensic science of determining how an accident occurred while assisting in the determination of the cause or why an accident or particular event during an accident happened using all available physical evidence.”
“This evidence can be in the form of tire marks, gouges, vehicle parts, vehicle damage, surveillance video, electronic vehicle information, occupant and pedestrian injuries, witness testimony, etc.”
“A collision reconstructionist takes all of the available evidence, like pieces in a puzzle, utilizes available tools and research, to put together the larger picture of the overall accident event.”
Excerpted from Collision research and analysis
Learning Standards
2016 Massachusetts Science and Technology/Engineering Curriculum Framework
HS-PS2-2. Use mathematical representations to show that the total momentum of a system of interacting objects is conserved when there is no net force on the system. Emphasis is on the qualitative meaning of the conservation of momentum and the quantitative understanding of the conservation of linear momentum in
interactions involving elastic and inelastic collisions between two objects in one dimension.
HS-PS2-3. Apply scientific principles of motion and momentum to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision. Clarification Statement: Both qualitative evaluations and algebraic manipulations may be used.
CCSS.MATH.CONTENT.7.EE.B.4 Use variables to represent quantities in a real-world or mathematical problem, and construct simple equations and inequalities to solve problems by reasoning about the quantities.
CCSS.MATH.CONTENT.8.EE.C.7 Solve linear equations in one variable
CCSS.MATH.CONTENT.HSA.SSE.B.3 Choose and produce an equivalent form of an expression to reveal and explain properties of the quantity represented by the expression. (including isolating a variable)
CCSS.MATH.CONTENT.HSA.CED.A.4 Rearrange formulas to highlight a quantity of interest, using the same reasoning as in solving equations. For example, rearrange Ohm’s law V = IR to highlight resistance R.
Declining Student Resilience
It has been widely reported that middle and high-school age students are suffering from much more depression, anxiety, dysphoria, and dysmorphia. Why is this?
Some social media posts suggest that this is related to the school closures due to the Covid-19 pandemic, and temporary social isolation that resulted. But numerous studies have shown that these massively increasing psychological problems among youth began a decade before this. Covid-19 only made these already existing issues more visible.
Studies show that declining student mental health and resilience is linked with the rise in use of social media, and the corrosive way that people use it and are affected by it.
Students who spend more time on social media, instead of interacting in the real world with peers, report more anxiety, depression, body dysmorphia, gender dysphoria, and symptoms related to anorexia.
Students who spend more time with friends and family, and community groups in the real world, report much less of this. Let’s be honest and ask two questions:
How many hours a week do typical students spend on cell phones and social media?
Pay attention closely – many kids underestimate the number of hours.
How many hours a week do typical students engage in healthy fun such as
playing outdoors at recess; playing outdoors after school and on weekends
Participating in the Boy scouts, Girl scouts, 4 H club, etc.
Helping neighbors at the senior center; spending time with their grandparents
Playing a musical instrument; being in a band or chorus
spending time with friends at church or synagogue youth groups
hanging out with friends at the beach, parks, or mall. Roller skating. Anything fun in a group.
I have many years of experience as a teacher; I’ve spent a lot of time listening to students about such things. Growing up, my friends and I spent well over 20 hours a week, collectively, on these things. To my dismay, in recent years most of my students report spending almost no time doing this. Rather, it’s mostly homework, social media, or social media-via-video gaming online.
As the articles below clearly show, human beings evolved outdoors as social beings. Nothing in our evolution prepared us for sitting still seven hours a day in school without recess, or sitting still for hours each day listening to toxic messages on social media.
This realization is not old people being grumpy, not keeping up with the times. The socially indoctrinated behaviors of today’s young people are demonstrably psychologically unhealthy.
I urge teachers, school counselors, and parents to read these articles –
Declining Student Resilience: A Serious Problem for Colleges
By Peter Gray, Psychology Researcher at Boston College, September 22, 2015
A year ago I received an invitation from the head of Counseling Services at a major university to join faculty and administrators for discussions about how to deal with the decline in resilience among students.
At the first meeting, we learned that emergency calls to Counseling had more than doubled over the past five years. Students are increasingly seeking help for, and apparently having emotional crises over, problems of everyday life.
Recent examples mentioned included a student who felt traumatized because her roommate had called her a [bad name] and two students who had sought counseling because they had seen a mouse in their off-campus apartment. The latter two also called the police, who kindly arrived and set a mousetrap for them.
Faculty at the meetings noted that students’ emotional fragility has become a serious problem when it comes to grading. Some said they had grown afraid to give low grades for poor performance, because of the subsequent emotional crises they would have to deal with in their offices. Many students, they said, now view a C, or sometimes even a B, as failure, and they interpret such “failure” as the end of the world.
Faculty also noted an increased tendency for students to blame them (the faculty) for low grades—they weren’t explicit enough in telling the students just what the test would cover or just what would distinguish a good paper from a bad one. They described an increased tendency to see a poor grade as reason to complain rather than as reason to study more, or more effectively.
Much of the discussions had to do with the amount of handholding faculty should do versus the degree to which the response should be something like, “Buck up, this is college.” Does the first response simply play into and perpetuate students’ neediness and unwillingness to take responsibility? Does the second response create the possibility of serious emotional breakdown, or, who knows, maybe even suicide?
Two weeks ago, that head of Counseling sent us all a follow-up email, announcing a new set of meetings. His email included this sobering paragraph:
“I have done a considerable amount of reading and research in recent months on the topic of resilience in college students. Our students are no different from what is being reported across the country on the state of late adolescence/early adulthood. There has been an increase in diagnosable mental health problems, but there has also been a decrease in the ability of many young people to manage the everyday bumps in the road of life. Whether we want it or not, these students are bringing their struggles to their teachers and others on campus who deal with students on a day-today basis. The lack of resilience is interfering with the academic mission of the University and is thwarting the emotional and personal development of students.”
The full article is available here Psychology Today: Declining student resilience, by Peter Gray
Decline of Play and the Rise of Psychopathology in Children and Adolescents
Over the past half century, in the United States and other developed nations, children’s free play with other children has declined sharply. Over the same period, anxiety, depression, suicide, feelings of helplessness, and narcissism have increased sharply in children, adolescents, and young adults. This article documents these historical changes and contends that the decline in play has contributed to the rise in the psychopathology of young people.
Play functions as the major means by which children (1) develop intrinsic interests and competencies; (2) learn how to make decisions, solve problems, exert self-control, and follow rules; (3) learn to regulate their emotions; (4) make friends and learn to get along with others as equals; and (5) experience joy. Through all of these effects, play promotes mental health. Key words: anxiety; decline of play; depression; feelings of helplessness;
free play; narcissism; psychopathology in children; suicide
The Decline of Play and the Rise of Psychopathology in Children and Adolescents
Helicopter Parenting & College Students’ Increased Neediness
In my last post, I summarized reports from directors of college counseling services concerning college students’ rising levels of depression and anxiety; declining abilities to cope effectively with problems of everyday life; and increasing feelings of entitlement … A common theory is that these changes may be at least partly attributable to a rise in “helicopter parenting”
… The theory makes sense, logically, but is there any empirical evidence? A first step in testing the theory is to look for correlations between the style of parenting and students’ emotional and behavioral well-being. Are students whose parents are highly controlling and intrusive more likely than others to manifest the kinds of problems reported by college counselors? A number of studies have examined this question, and the results of all that I have found indicate that the answer is yes.
Helicopter Parenting & College Students’ Increased Neediness
Researchers link helicopter parenting to emotional fragility in young adults.
Peter Gray, Psychology Today, Oct 23, 2015
The Many Shades of Fear-Based Parenting
I have long been advocating, on this blog and elsewhere, for what I refer to as trustful parenting. Trustful parents allow their children as much freedom as reasonably possible to make their own decisions. They trust their children’s instincts, judgments, and ability to learn from mistakes….
The enemy of trustful parenting is fear, and, unfortunately, fear runs rampant in our society today. It runs rampant not because the world is truly more dangerous than it was in the past, but because we as a society have generated dangerous myths about dangers. We are afraid that strangers will snatch our children away if we don’t guard them constantly and that our children will be homeless, or in some other way life failures, if they don’t get all As in school, do all the proper extracurricular activities, and get into a top-ranked college…
Fear-based parenting comes in various shades, depending partly on the types of fears most prominent in the parents’ minds and partly on the parents’ personalities and economic means. Here is a list.
The Many Shades of Fear-Based Parenting, Peter Gray, Psychology Today, Mar 25, 2019
Doing More Time in School
Those who want more forced schooling ignore students’ opinions.
by Peter Gray
Kids aren’t learning much in school, so let’s make them start school when they are younger; let’s make them stay more hours in school each day and more days each year; and let’s not allow them to leave until they are at least 18 years old. Let’s do all this especially to the poor kids; they are getting the least out of school now, so let’s lengthen their time in school even more than we lengthen the time for others!…
School districts now go so far as to ban ‘tag’
Schools are contributing to mental health problems in children by banning normal, healthy forms of play and social interaction. Many now claim that even tag is too emotionally and physically dangerous to kids.
http://www.freerangekids.com/school-district-bans-tag-for-students-physical-and-emotional-safety/
Children are literally not free to play outside
From the article
As if parents don’t have enough to worry about in the midst of a pandemic, last week, I got a terribly upsetting email from a dad who wrote to say that Child Protective Services, or CPS, had come to investigate him. Not because his kids weren’t social distancing. Not because of any beatings or starvation or deliberate exposure to dangerous germs.
He was being investigated for allowing his kids, ages 6 and 3, to play on their own front lawn.
The email came to me from a dad in Texas. He wrote, “While letting my kids play in my front yard, I got CPS called on me. I wasn’t out there with them but I was going out every 5 to 10 minutes and watching through the window between checks.” When the caseworker arrived, his son made some popcorn, and the caseworker commented on how self-reliant he was. But self-reliant or not, the caseworker added, Dad had to be by his kids’ side at all times.
That is simply not true.
“Misstatements of law like this happen all around the country,” says longtime Chicago-based child welfare lawyer Diane Redleaf. “Neglect laws are intended to protect children from serious harm. That’s why it is more important than ever to get child protection policy right.”
The idea that kids can’t play on their own lawn, lightly supervised, is nonsensical in the best of times. When there’s a pandemic and kids are cooped up 24/7 for weeks at a time, it is even more important that we all understand: Kids need some play time. Parents need some work time. Even if helicopter parenting was the crazy norm before, it’s impossible now.
From Kids Deserve Playtime Without Their Parents Getting Arrested, Lenore Skenazy, The Sun (newspaper) 4/27/2020
Scientific studies of cell phone usage and mental health
Excessive Smartphone Use Is Associated With Health Problems in Adolescents and Young Adults
Yehuda Wacks and Aviv M. Weinstein*
They report that excessive cell phone usage leads to depression, anxiety, OCD, ADHD, alcohol abuse, cognitive-emotion regulation, impulsivity, impaired cognitive function, addiction to social networking, shyness and low self-esteem, sleep problems, reduced physical fitness, unhealthy eating habits, pain and migraines, reduced cognitive control and changes in the brain’s gray matter volume.
Cell phones, Teens and Mental Health
Two recent studies shed light on the negative psychological consequences of social media use.
There is no doubt that smartphone use has become pervasive in our society. In a 2018 Pew Research Center poll, 95 per cent of teens reported having access to a smart phone. Some 45 per cent of teens reported using the internet “almost constantly” (a number that has doubled compared to the 2014-2015 survey), while another 44 per cent said they go online multiple times per day.
The negative potential for social media was highlighted in two recent studies. In the first, researchers found that in a cohort of 6,595 U.S. adolescents, those who used social media more than three hours per day were at increased risk for developing mental health problems. The risk was principally seen for internalizing problems such feeling lonely, sad, depressed or anxious rather than for externalizing problems like acting out or behaviour difficulties.
The second study was an analysis of more than 12,000 teenagers in England. English teenagers were even more active on social media than their American counterparts. Two in three teens ages 15 to 16 used social media multiple times per day.
The researchers also found that teens who used social media multiple times per day were more likely to report psychological distress, less life satisfaction, less happiness and more anxiety than those who used it only weekly or less often. An interesting aspect of the study was that the negative effects of social media were more prominent in girls than boys. While both boys and girls showed an increase in psychological distress, the magnitude of the increase was higher in girls (18 per cent) than in boys (5 per cent).
Kinematics in music videos
Kinematics is the study of objects in motion. One uses math to analyze distance, displacement, speed, velocity, and acceleration. It even finds a use in music videos
“The One Moment” is from OK Go’s 2014 full-length, Hungry Ghosts
New video on NPR.org
http://okgo.net/2016/11/23/background-notes-and-full-credits-for-the-one-moment-video/
https://www.youtube.com/user/OkGo/videos
Background notes and full credits for “The One Moment” Video by OK Go.
Damian Kulash, Jr. (director and singer)
The song “The One Moment” is a celebration of (and a prayer for) those moments in life when we are most alive. Humans are not equipped to understand our own temporariness; It will never stop being deeply beautiful, deeply confusing, and deeply sad that our lives and our world are so fleeting. We have only these few moments. Luckily, among them there are a few that really matter, and it’s our job to find them. (We had no idea when we wrote the song that we’d be releasing its video in such critical moment for our nation and the world. It’s one of those moments when everything changes, whether we like it or not, so the song feels particularly relevant)
For the video, we tried to represent this idea literally — we shot it in a single moment. We constructed a moment of total chaos and confusion, and then unraveled that moment, discovering the beauty, wonder, and structure within.
Most of our videos have sought to deliver wonder and surprise, and this one is no exception. But usually our tone has been more buoyant, more exuberant. For this song — our most heartfelt and sincere — we wanted the sense of wonder to be more intimate and contemplative…
How did you do that?
We used very precise digital triggers to set off several hundred events in extremely quick succession.
The triggers were synchronized to high speed robotic arms which whipped the cameras along the path of the action.
Though the routine was planned as a single event, currently no camera control systems exist which could move fast enough (or for many sections, change direction fast enough) to capture a movement this long and complex with a single camera, so the video you see connects seven camera movements.
How long did the routine take in real time?
The first three quarters of the video, from the beginning of the song until I pick up the umbrella at the a cappella breakdown, unfold over 4.2 seconds of real time. Then I lip sync in real time for about 16 seconds (we thought it was important to have a moment of human contact at this point in the song, so we returned to the realm of human experience) and we return to slow motion for the final chorus paint scene, which took a little longer than 3 seconds in real time.
How many things happen in it?
It sort of depends how you count “things,” but the there are 318 events (54 colored salt bursts behind Tim, 23 exploding paint buckets, 128 gold water balloons, etc.) that were synchronized to the music before the breakdown. After that there are only 9 digitally triggered events.
Just how slow is this, and is it all one speed?
It is not all one speed, but each section is at a constant rate, meaning that time does not “ramp” (accelerate or decelerate). We just toggle from one speed to another. When the guitars explode, we are 200x slower than reality (6,000 frames per second), but Tim and Andy’s short bursts of lip sync (Tim twice and Andy once) are only 3x slower than real life (90 frames per second). The watermelons are around 150x, and the spray paint cans are a little over 60x.
How did you plan all this?
The whole point of the video is to explore a time scale that we can’t normally experience, but because it’s so inaccessible to us, our tools for dealing with it are indirect. The only way we can really communicate with that realm is through math. The choreography for this video was a big web of numbers — I made a motherfucker of a spreadsheet. It had dozens of connected worksheets feeding off of a master sheet 25 columns wide and nearly 400 rows long. It calculated the exact timing of each event from a variety of data that related the events to one another and to the time scale in which they were being shot. Here’s a screen shot of just the first few lines, to give you a sense.

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Example of a high speed robotic camera arm
http://www.8k-47.com/technologies/bolt-highspeed-cinebot/
http://www.roboticgizmos.com/spike-robotic-motion-control-camera-system/
http://www.mrmoco.com/thebolt/
https://www.youtube.com/watch?v=HRvnYmxcMOY
Internal reflection
Physics is a deeply conceptual class. It’s not like English or History, where everyone already knows vast amounts of content before even entering. Students entering high school already knowing what a story is, what characters are, what a theme is, and what a moral is.
The human themes discussed by Shakespeare or Homer are universal. They are intuitively understood by even the least prepared of readers. Students may not know much about Elizabethan England, or ancient Greece, but they know what it means to be happy, sad, angry, or jealous. They know what it means for a character to fall in love, or to flee from their home.
When they read about a King entering a castle, and making a pronouncement to the citizens, students get it right away. Does any student ever erroneously think that “the pronouncement” is a person? That “the King” is a large object built out of wood and stone that someone lives in? That “the Castle” is a letter to be read? Of course not.
This is not so, however, with concepts in physics. Student entering a physics class often have no meaningful understanding of conservation laws, or Newton’s laws of motion. Most don’t understand why it is essential to differentiate between conservation of energy and conservation of momentum. When someone doesn’t know if a problem requires conservation of energy concepts, or kinematic equation concepts to solve a problem, that’s a like a person not knowing the difference between a King and a Castle. It is that basic.
Outside of AP Physics we usually are teaching from the ground level upwards.
No teaching method, homework assignment, or pedagogical technique has much effect on student performance – unless that student takes time to engage in internal mental reflection.
When students review at home what we learned in class,
When students think about what happened, and why it happened,
When students compare their preconceptions to what they have observed
only they are engaging in internal mental reflection.
If a student chooses not do this, then there is little a teacher can add. We can explain it for you, but we can’t understand it for you.
This is one reason why some students struggle. Doing classwork has only limited usefulness, unless one internally reflects on the subject.
How to be a good student
Chapter 12. Learning Through Reflection, by Arthur L. Costa and Bena Kallick
Learning Through Reflection
Google Scholar Search
Aristotle’s laws of motion
Aristotle (Ἀριστοτέλης) 384–322 BCE was a Greek philosopher and scientist born in the city of Stagira, in classical Greece.

At 17 years of age, he joined Plato’s Academy in Athens and remained there until the age of thirty-seven (c. 347 BCE)

His writings cover many subjects – including physics, biology, zoology, logic, ethics, poetry, theater, music, linguistics, and politics. They constitute the first comprehensive system of Western philosophy.
Shortly after Plato died, Aristotle left Athens and, at the request of Philip of Macedon, tutored Alexander the Great beginning in 343 BC.
Aristotle’s views on physical science profoundly shaped medieval scholarship. Their influence extended from Late Antiquity and the Early Middle Ages into the Renaissance, and were not replaced systematically until the Enlightenment and theories such as classical mechanics.
- excerpted and adapted from Aristotle. (2016, October 20). Wikipedia, The Free Encyclopedia.
___________________________
Aristotle’s laws of motion

Aristotle set out 3 laws of motion, based on observations (but not on experiment)
* objects fall at a constant rate, that depends on their size and weight.
* there is a difference between “violent motion” versus “natural motion”
* objects in the heavens (the celestial sphere) move in circular motion, without any external force compelling them to do so.
objects on Earth (the terrestrial sphere) move in straight lines, unless forced to move in a circular motion.
Here is the modern, correct view of how gravity accelerates objects of different masses.
(Does the mass and size affect the speed at which they fall?)
Yet here is Aristotle’s view of how gravity accelerates objects of different masses.
(How does this differ from the previous animation?)
What about pushing and pulling?
Natural vs Unnatural Motion
For objects on Earth, Aristotle thought that objects moved by people (“unnatural motion”) would move in a straight line, and when that “unnatural force” ran out, then natural motion would take over.
So what would happen if a canon fired a cannonball? Aristotle supposed that it would move in a straight line (due to the unnatural force), and then would fall straight down (due to a different, natural force.)

For Aristotle, once “violent motion” (from people) extinguished itself, natural motion takes over, and then the cannon ball falls to its natural place, the earth.
An animation of what this would look like.
However, as Galielo showed in the 1500’s, Aristotle’s view isn’t correct at all. Anyone who watches an archer fire an arrow into the air, and carefully observes, would see that this doesn’t happen.
Galileo showed that the vertical motion (up/down) and horizontal motion (size-to-side) are independent.
When you fire an arrow, cannonball, or pop-fly in baseball, into the air, what happens?
The vertical motion slowly decreases, reaches zero (at the peak), and then increases in the opposite (downward) direction.
The horizontal motion actually stays constant (doesn’t speed up, or slow down.)
Heavenly forces vs terrestrial forces
Aristotle thought that heavenly (celestial) objects, by their nature, forever moved in circles – without any external force acting on them.
Earthly (terrestrial) objects were believed to have a separate set of laws of motion. Earthly objects supposedly would always stop moving, of their own accord, on their own.
As we will learn, there aren’t really 2 sets of laws (heavenly and earthly); rather, the laws of nature are the same everywhere:
* objects naturally travel only in straight lines.
* for objects to have a circular motion requires some external force, keeping them pulled into a circular path
How could one of the greatest thinkers of the classical world be in error? The ancient Greeks had a preference for attempting to find truth through logic alone. Greeks viewed observations of the physical world as a valid way to learn, but held this to be inferior to intellect.
Also, Aristotle never ran experiments, so he was very limited in what he could observe. In the medieval era, Galileo (and others) ran controlled experiments. The results of these experiments were analyzed with math.
Their findings ended the acceptance of Aristotelian physics.
Galileo learned critical thinking skills from his father, Vincenzo
Galileo and Einstein: History of Physics – Prof Michael Fowler
Galileo continued his father’s tradition of critical inquiry
Galileo rolled balls along surfaces tilted at different angles.
a. When ball rolls downward, it moves with Earth’s gravity, and its speed increases.
b. When ball rolls upward, it moves against gravity and loses speed.
c. When ball rolls on level plane, it doesn’t move with or against gravity.
a. The ball rolls down the incline, and then up the opposite incline,
and reaches its initial height.
b. As the angle of the upward incline is reduced, the ball rolls a greater distance before reaching its initial height.
c. If there is no friction, then the ball will never stop – unless it hits something.
Galileo’s conclusion was supported by another line of reasoning.
He described two inclined planes facing each other.
A ball released to roll down one plane would roll up the other to reach nearly the same height.
The smoother the planes were, the more nearly equal would be the initial and final heights.
He noted that the ball tended to attain the same height, even when the second plane was longer and inclined at a smaller angle than the first plane.
Always, the ball went farther and tended to reach the same height.
Inclined Plane – Galileo’s Battle for the Heavens PBS NOVA
Video clip: Galileo’s inclined plane PBS media
Advanced: Similar studies with the moment of inertia
Rolling balls, cylinders and tubes down inclined plane: Moment of Inertia
Something special: The brachistochrone – curve of quickest descent. And the tautochrone- the curve for which the time taken by an object sliding without friction in uniform gravity to its lowest point is independent of its starting point.

Aristotle’s laws of motion
Excerpted from a lecture by Professor Michael Fowler, U. Va. Physics, 9/3/2008
http://galileoandeinstein.physics.virginia.edu/lectures/aristot2.html
What Aristotle achieved in those years in Athens was to begin a school of organized scientific inquiry on a scale far exceeding anything that had gone before. He first clearly defined what was scientific knowledge, and why it should be sought. In other words, he single-handedly invented science as the collective, organized enterprise it is today. Plato’s Academy had the equivalent of a university mathematics department, Aristotle had the first science department, truly excellent in biology, but, as we shall see, a little weak in physics.
After Aristotle, there was no comparable professional science enterprise for over 2,000 years, and his work was of such quality that it was accepted by all, and had long been a part of the official orthodoxy of the Christian Church 2,000 years later. This was unfortunate, because when Galileo questioned some of the assertions concerning simple physics, he quickly found himself in serious trouble with the Church.
Aristotle’s method of investigation:
defining the subject matter
considering the difficulties involved, by reviewing the generally accepted views on the subject, and suggestions of earlier writers
presenting his own arguments and solutions
This is the pattern modern research papers follow, Aristotle was laying down the standard professional approach to scientific research.
Aristotle often refuted an opposing argument by showing that it led to an absurd conclusion, this is called reductio ad absurdum (reducing something to absurdity). As we shall see later, Galileo used exactly this kind of argument against Aristotle himself, to the great annoyance of Aristotelians [people who fully agreed with Aristotle] 2,000 years after Aristotle.
[Aristotle himself likely would not have minded later thinkers disagreeing with him;
in his lifetime Aristotle would change his mind if he found new information or a more logical argument.]
In contrast to Plato, who felt the only worthwhile science to be the contemplation of abstract forms, Aristotle practiced detailed observation and dissection of plants and animals, to try to understand how each fitted into the grand scheme of nature, and the importance of the different organs of animals.
It is essential to realize that the world Aristotle saw around him in everyday life was very different indeed from that we see today. Every modern child has since birth seen cars and planes moving around, and soon finds out that these things are not alive, like people and animals. In contrast, most of the motion seen in fourth century Greece was people, animals and birds, all very much alive. This motion all had a purpose, the animal was moving to someplace it would rather be, for some reason, so the motion was directed by the animal’s will.
For Aristotle, this motion was therefore fulfilling the “nature” of the animal, just as its natural growth fulfilled the nature of the animal.
To account for motion of things obviously not alive, such as a stone dropped from the hand, Aristotle extended the concept of the “nature” of something to inanimate matter. He suggested that the motion of such inanimate objects could be understood by postulating that elements tend to seek their natural place in the order of things:
So earth moves downwards most strongly, water flows downwards too, but not so strongly, since a stone will fall through water. In contrast, air moves up (bubbles in water), and fire goes upwards most strongly of all, since it shoots upward through air.
This general theory of how elements move has to be elaborated, of course, when applied to real materials, which are mixtures of elements. He would conclude that wood has both earth and air in it, since it does not sink in water.
Natural Motion and Violent Motion
Things also move because they are pushed. A stone’s natural tendency, if left alone and unsupported, is to fall, but we can lift it, or even throw it through the air.
Aristotle termed such forced motion “violent” motion as opposed to natural motion.
The term “violent” just means that some external force is applied to it.
Aristotle was the first to think quantitatively about the speeds involved in these movements. He made two quantitative assertions about how things fall (natural motion):
Heavier things fall faster, the speed being proportional to the weight.
The speed of fall of a given object depends inversely on the density of the medium it is falling through.
So, for example, the same body will fall twice as fast through a medium of half the density.
Notice that these rules have a certain elegance, an appealing quantitative simplicity. And, if you drop a stone and a piece of paper, it’s clear that the heavier thing does fall faster, and a stone falling through water is definitely slowed down by the water, so the rules at first appear plausible.
The surprising thing is, in view of Aristotle’s painstaking observations of so many things, he didn’t check out these rules in any serious way.
It would not have taken long to find out if half a brick fell at half the speed of a whole brick, for example. Obviously, this was not something he considered important.
From the second assertion above, he concluded that a vacuum cannot exist, because if it did, since it has zero density, all bodies would fall through it at infinite speed which is clearly nonsense.
For violent motion, Aristotle stated that the speed of the moving object was in direct proportion to the applied force.
This means first that if you stop pushing, the object stops moving.
This certainly sounds like a reasonable rule for, say, pushing a box of books across a carpet, or an ox dragging a plough through a field.
This intuitively appealing picture, however, fails to take account of the large frictional force between the box and the carpet. If you put the box on a sled and pushed it across ice, it wouldn’t stop when you stop pushing. Centuries later, Galileo realized the importance of friction in these situations.
Learning Standards
2016 Massachusetts Science and Technology/Engineering Curriculum Framework
HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion is a
mathematical model describing change in motion (the acceleration) of objects when
acted on by a net force.
HS-PS2-10(MA). Use free-body force diagrams, algebraic expressions, and Newton’s laws of motion to predict changes to velocity and acceleration for an object moving in one dimension in various situations
Massachusetts History and Social Science Curriculum Framework
The roots of Western civilization: Ancient Greece, C. 800-300 BCE.
7.34 Describe the purposes and functions of development of Greek institutions such as the lyceum, the gymnasium, and the Library of Alexandria, and identify the major accomplishments of the ancient Greeks.
WHI.33 Summarize how the Scientific Revolution and the scientific method led to new theories of the universe and describe the accomplishments of leading figures of the Scientific Revolution, including Bacon, Copernicus, Descartes, Galileo, Kepler, and Newton.
A FRAMEWORK FOR K-12 SCIENCE EDUCATION: Practices, Crosscutting Concepts, and Core Ideas
PS2.A: Forces and motion – How can one predict an object’s continued motion, changes in motion, or stability?
Interactions of an object with another object can be explained and predicted using the concept of forces, which can cause a change in motion of one or both of the interacting objects… At the macroscale, the motion of an object subject to forces is governed by Newton’s second law of motion… An understanding of the forces between objects is important for describing how their motions change, as well as for predicting stability or instability in systems at any scale.
Math is the language of physics
Mathematics is the language of physics
Natural philosophy [i.e., physics] is written in this grand book – I mean the universe – which stands continually open to our gaze, but it cannot be understood unless one first learns to comprehend the language and interpret the characters in which it is written.
[The universe] cannot be read until we have learned the language and become familiar with the characters in which it is written. It is written in mathematical language, and the letters are triangles, circles and other geometrical figures, without which means it is humanly impossible to comprehend a single word.
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Galileo, Opere Il Saggiatore p. 171
Mathematics is the language of physics. Physical principles and laws, which would take two or even three pages to write in words, can be expressed in a single line using mathematical equations. Such equations, in turn, make physical laws more transparent, interpretation of physical laws easier, and further predictions based on the laws straightforward.
-
Mesfin Woldeyohannes, Assistant Professor, Western Carolina University
ἀεὶ ὁ θεὸς γεωμετρεῖ – Aei ho theos geōmetreî. God always geometrizes.
-
Plato, 400 BCE, classical Greece, as quoted by Plutarch in his The Moralia, Quaestiones convivales. (circa 100 CE)
Math is so useful in the real world that it’s eerie
There is a classic paper, The Unreasonable Effectiveness of Mathematics in the Natural Sciences, that it should be read even by high school students.
Wigner begins his paper with the belief, common among those familiar with mathematics, that mathematical concepts have applicability far beyond the context in which they were originally developed.
Based on his experience, he says “it is important to point out that the mathematical formulation of the physicist’s often crude experience leads in an uncanny number of cases to an amazingly accurate description of a large class of phenomena.”
Wigner then invokes the fundamental law of gravitation as an example. Originally used to model freely falling bodies on the surface of the earth, this law was extended on the basis of what Wigner terms “very scanty observations” to describe the motion of the planets, where it “has proved accurate beyond all reasonable expectations”.
Another oft-cited example is Maxwell’s equations, derived to model the elementary electrical and magnetic phenomena known as of the mid 19th century. These equations also describe radio waves, discovered by David Edward Hughes in 1879, around the time of James Clerk Maxwell’s death.
Wigner sums up his argument by saying that “the enormous usefulness of mathematics in the natural sciences is something bordering on the mysterious and that there is no rational explanation for it”. He concludes his paper with the same question with which he began:
The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve. We should be grateful for it and hope that it will remain valid in future research and that it will extend, for better or for worse, to our pleasure, even though perhaps also to our bafflement, to wide branches of learning.
-
The Unreasonable Effectiveness of Mathematics in the Natural Sciences. (2016, September 11). In Wikipedia, The Free Encyclopedia
The Unreasonable Effectiveness of Mathematics in the Natural Sciences
Math is different from physics
Mathematics does not need to bother itself with real-world observations. It exists independently of any and all real-world measurements. It exists in a mental space of axioms, operators and rules.
Physics depends on real-world observations. Any physics theory could be overturned by a real-world measurement.
None of maths can be overturned by a real-world measurement. None of geometry can be.
Physics starts from what could be described as a romantic or optimistic notion: that the universe can be usefully described in mathematical terms; and that humans have the mental ability to assemble, and even interpret, that mathematical description.
Maths need not concern itself with how the universe actually works. Perhaps there are no real numbers, one might think it is likely that there is only a countable number of possible measurements in this universe, and nothing can form a perfect triangle or point.
Maths, including geometry, is a perfect abstraction that need bear no relation to the universe as it is.
Physics, to have any meaning, must bear some sort of correspondence to the universe as it is.
Why-is-geometry-mathematics-and-not-physics? Physics StackExchange, by EnergyNumbers
Related articles
What is mathematics, really? Is it made by humans or a feature of the universe? Math in art & poetry.
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Thanks for reading. While you’re here see our articles on astronomy, biology, chemistry, Earth science, physics, the scientific method, and making connections to science through reading, books, TV and movies.
Scratch Resources

Resources
The Pen is a feature in Scratch that allows a Sprite to draw shapes, plot colored pixels, and so forth on the screen with the Pen Blocks. Lines, dots, rectangles, and circles are the easiest shapes to draw, but with enough scripting, any shape can be created.
https://wiki.scratch.mit.edu/wiki/Pen
A graphic effect is an effect that can be used on a sprite or the Stage, changing their look in some way. These blocks can be found under the Looks section. No effect, color, fisheye, whirl, pixelate, brightness, ghost, mosaic
https://wiki.scratch.mit.edu/wiki/Graphic_Effect
Projects
Plot a line ( y=mx +b) Hit ‘space’ to plot a line and the c key to clear the old lines.
https://scratch.mit.edu/projects/20613546/
Speed=Distance/Time: Doesn’t actually calculate numerical answers. Instead, it changes the size of the S, D and T graphical icons according to their value.
https://scratch.mit.edu/projects/97105344/
Make your own line graph (primitive)
https://scratch.mit.edu/projects/51897174/
Drawing fractals
http://www.edutopia.org/blog/scratch-programming-advanced-fractal-fun-dylan-ryder
Advanced projects using physics and math:
-Use Trigonometric principles to determine Vectors for X and Y Directions for Sprite(Object) Movement.
-Simulate Gravity Physics.
-Use Conditional Statements and While Loops (Repeat Until) to determine action within Game.
– Use Variables to store, calculate, and direct movement within Game/Simulation.
http://nebomusic.net/advancedscratch.html
CoderDojo: AthenryMultiple advance Scratch topics
https://coderdojoathenry.org/category/scratch-advanced/
Building a 3D wireframe
https://coderdojoathenry.org/2016/04/17/scratch-advanced-general-purpose-wireframe-3d-engine/
Galaga classic video game
https://scratch.mit.edu/projects/10076961/
Building a platforming game in Scratch
https://www.scribd.com/doc/131949494/Building-a-platform-game-with-Scratch
MIT’s Scratch Part 4: Twenty Webs Sites To Support Scratch And The Itch For Transforming Education
Teach-ict – 5 projects (7 hours+) for fully functional games.
Teach-ict.com programming/scratch/scratch_home.htm
Mathematics problems
https://scratch.mit.edu/studios/6423/
Recommended books
Scratch Programming for Teens PDF book free online
Adventures in Coding, Eva Holland and Chris Minnick
Scratch Programming Playground: Learn to Program by Making Cool Games, by Al Sweigart
Scratch 2.0 Sams Teach Yourself in 24 Hours, by Timothy L. Warner




























