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Traditional physics labs
Egg-cellent Ideas for Osmosis and Diffusion
Basic ideas behind diffusion:
Basic idea behind osmosis
Lab from sciencespot.net
Submitted by Sue Remshak, Lake Bluff Middle School, Lake Bluff, IL
During this activity students investigate the concepts of osmosis and diffusion using eggs. To prepare for the activity,:
* measure and record the circumference of the raw egg
* measure mass.
* Place the egg in a beaker filled with white vinegar.
* Students to record their observations.
* Store the eggs in a refrigerator for 24 hours.
* View again and record their observations.
* Return the egg to the refrigerator for another 24 hours.
* View again and record their observations
Student worksheet: http://sciencespot.net/Pages/osmdiff.html
A chemical reaction occurs between the vinegar and the calcium carbonate in the egg shell. The bubbles of carbon dioxide that form on the egg and rise to the surface are evidence of this reaction. The shell dissolves in the vinegar and leaves a film on the surface of the vinegar.
However, the membrane remains on the egg. The size of the egg increases because of the movement of water in the vinegar through the cell membrane.
Since water moves from an area of high concentration to an area of low concentration, this process is called osmosis. Obviously, none of the materials on the inside of the egg are able to pass through the membrane.
Materials: water, blue water (food coloring in water), molasses, and corn syrup.
First, have the students determine the mass of the egg and record it in the table.
They should pour 150 ml of each substance into its own beaker.
Add the eggs and store in a refrigerator for 24 hours.
After 24 hours, remove the eggs from the beakers and record their observations.
Students should record the volume of liquid in the beaker as well as the mass of the egg.
Use a toothpick to pop the egg membrane and record their observations. Be sure to have paper towels handy as some eggs may squirt!)
The egg in plain water and blue water will become slightly larger because water will pass into egg through the membrane by the process of osmosis. There will be blue food coloring in the egg from the blue water since both water and food coloring can pass through the membrane.
The egg in corn syrup and molasses will decrease in size because water from inside the egg flow through the membrane into the syrup or molasses. It moves from a higher concentration inside the egg to a lower concentration in the corn syrup. Once again, this is called osmosis. The corn syrup and molasses molecules are too large to pass through the membrane. Observant students will not only notice an increase of volume in the beaker, but they will also see a thin layer of water resting on top of the syrup and molasses.
To illustrate the concept of diffusion, add a drop or two of extract (vanilla, bubble gum, lemon, or cinnamon) into a deflated balloon.
Blow up the balloon, tie it off, and place inside a shoe box. To make sure the lid stays on the box, use masking tape to secure it. During class, ask students to life one end of the shoe box lid and smell the contents. Their eyes should remain closed when they do this. Ask each student to reveal what they smelled. Show the class what was inside the box and instruct them to draw a picture and record their observations. Challenge students to write an explanation (using the correct vocabulary) of why the box smells like the scent when it was only put inside the balloon.
The shoe box smelled of the scent even though it was only placed on the inside of the balloon due to the process of diffusion. Every balloon has microscopic holes in its surface. The vapors were able to pass through the membrane from an area of high concentration to an area of low concentration. However, the liquid scent molecules were too large to pass through the membrane.
Another way to illustrate osmosis and diffusion is using a tea bag and some water. During class, place a tea bag in a beaker of warm water. Allow time for students to record their observations. Challenge them to write an explanation using the correct vocabulary.
Water flows by osmosis into the tea bag. The students can see this if you remove the tea bag from the beaker and squeeze it to see the water come out. The tea leaves diffuse through the tea bag and into the water; this changes both the color and flavor of the water in the beaker.
At Seaport Academy, science education isn’t about drills and worksheets. We motivate students with hands-on manipulatives, interactive apps, three dimensional animations, connections to the world around then, and labs. Here we’re learning how to explore the microscopic world with a microscope.
We examine animal fur, scales and skin, plant pollen, seeds and leaves, and insect parts.
Here we see a student’s point-of-view when discovering the anatomy of a honeybee leg.
Used when a specimen is translucent (some light passes thru it)
Usually higher power 10x to 300x
The observer sees all the way thru the specimen being studied.
Has more than two sets of lenses.
Has an eyepiece lens (or ocular) and two or more sets of objective lenses
They sit on on a nosepiece that can revolve
The specimen is placed on the stage of this microscope.
Parts of the microscope
eyepiece (ocular) – where you look through to see the image
body tube – Holds the eyepiece and connects it down to the objectives
fine adjustment knob – Moves the body of the microscope up/down more slowly; fine control. Gets the specimen exactly focused. We only use this after we first use the coarse adjustment knob.
nosepiece – rotating piece at the bottom of the body tube. Lets us choose between several lenses (objectives.)
high power objective — used for high power magnification (the longer objective lens)
low power objective — used for low power magnification
diaphragm – controls amount of light going through the specimen
light/mirror – source of light, usually found near the base of the microscope.
base – supports the microscope
coarse adjustment knob — Moves body of the microscope up/down more quickly; Gets specimen approximately focused.
arm – Holds main part of the microscope to the base.
stage clips – hold the slide in place.
inclination joint – used to tilt the microscope
College Board Standards for College Success: Science
LSM-PE.2.1.2 Gather data, based on observations of cell functions made using a microscope or on cell descriptions obtained from print material, that can be used as evidence to support the claim that there are a variety of cell types.
LSM-PE.2.2.1 Describe, based on observations of cells made using a microscope and on information gathered from print and electronic resources, the internal structures (and the functions of these structures) of different cell types (e.g., amoeba, fungi, plant root, plant leaf, animal muscle, animal skin).
Inquiry, Experimentation, and Design in the Classroom: SIS2. Design and conduct scientific investigations. Properly use instruments, equipment, and materials (e.g., scales, probeware, meter sticks, microscopes, computers) including set-up, calibration (if required), technique, maintenance, and storage.
I. Build and demonstrate a hovercraft, or
II. Write a typed report, with a cover page, 3 double-spaced pages of text, and 1 page of citations/references, on what a hovercraft is, how they work, and how they use Newton’s laws of motion, or
III. Create a computer presentation on what a hovercraft is, how they work, and how they use Newton’s laws of motion. Present it to the class.
You may use software such as Microsoft PowerPoint, OpenOffice Impress, Corel Presentations, or any other software you like. All of these programs are very similar. OpenOffice is a package of programs very much like MS Office, but totally free. http://www.openoffice.org/
The entire project may be found in this document: TO BE ADDED
How to build your own hovercraft
Kelvin Educational Kits
EGR 100 — Hovercraft Design Project: College freshmen majoring in engineering build and design hovercrafts
Hovercraft calculator – used only for building larger hovercraft that can actually carry passengers.
2016 Massachusetts Science and Technology/Engineering Curriculum Framework
HS-ETS4-5(MA). Explain how a machine converts energy, through mechanical means, to do work. Collect and analyze data to determine the efficiency of simple and complex machines.
HS-PS3-3. Design and evaluate a device that works within given constraints to convert one form of energy into another form of energy.
• Emphasis is on both qualitative and quantitative evaluations of devices.
• Examples of devices could include Rube Goldberg devices, wind turbines, solar cells, solar ovens, and generators.
Appendix VIII Value of Crosscutting Concepts and Nature of Science in Curricula
Cause and Effect: Mechanism and Explanation. Events have causes, sometimes simple, sometimes multifaceted. A major activity of science and engineering is investigating and explaining causal relationships and the mechanisms by which they are mediated. Such mechanisms can then be tested across given contexts and used to predict and explain events in new contexts or design solutions.
College Board Standards for College Success: Science
Standard PS.1 Interactions, Forces and Motion
Changes in the natural and designed world are caused by interactions. Interactions of an object with other objects can be described by forces that can cause a change in motion of one or both interacting objects. Students understand that the term “interaction” is used to describe causality in science: Two objects interact when they act on or influence each other to cause some effect. Students understand that observable objects, changes and events occur in consistent patterns that are comprehensible through careful, systematic investigations.
Next Generation Science Standards: Science – Engineering Design (6-8)
• Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.