I made ScienceFix.com to share my favorite demos that I do in my middle school science classes.  

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Entries in demo (81)


Video Demo: Strikeless Matches

Activation energy is the minimum amount of energy needed to start a chemical reaction. Many chemical reactions don’t need a lot of energy to react. A classic example when baking soda mixes with vinegar. The heat energy that is in the environment is enough to start this chemical reaction. Other chemical reactions need a higher amount of energy. A match lighting is one example. When a match strikes, the friction produces heat energy. This heat energy is the activation energy that starts the chemical reaction. In the following demo three matches are tied together with thread and placed into a flask that is covered with a piece of aluminum foil. The bottom part of the matches touches the bottom of the flask. The flask is placed on a hot plate on the high setting. The hot plate provides the energy to start the chemical reaction between the matches and oxygen that is in the flask.


Video Demo: Yeast Cellular Respiration

This demo demonstrates that yeast do cellular respiration. When sugar (glucose) and oxygen are present, yeast mitochondria will make those chemicals react and release energy as well as the products water and carbon dioxide. Bromothymol blue solution will change to yellow in the presence of carbon dioxide. If there is no more oxygen, then yeast cells will shift to fermentation.


Video Demo: Whiteboard Protein Synthesis Demo

Protein synthesis is the process that the cell goes through to make a protein from the information stored in the DNA. The video below shows a demonstration that you can do in your classroom to show how protein synthesis works. This demonstration emphasizes the following points:

1. DNA contains the information to make a specific protein.
2. The DNA is in the nucleus of the cell.
3. The DNA cannot leave the nucleus.
4. The ribosomes make the protein from the information.
5. The ribosomes are in the cytoplasm and cannot go into the nucleus.

The metaphor that I use in class is that the DNA is like a series of recipe books in the library. These books cannot be checked out/taken out of the library. The only way to get the information that is in the books out of the library is to make a copy. mRNA is the copy of the information that can leave the nucleus and go into the cytoplasm so that the ribosome can read and make the protein. Watch the video to see how it comes all together.

Teaching tips: Place the amino acids around the classroom (cytoplasm). Assign students to be specific tRNA’s. They will get the specific amino acid and bring it to the ribosome for you.


Video Demo: Accelerometer

Acceleration is the change in velocity over time. Velocity changes when speed, direction, or both changes. Anyone can build a simple accelerometer. The video below shows how to build an accelerometer and how to use it.


Video Demo: Laser Lens Eye

Teaching how the eyeball works usually involves showing diagrams of the eyeball and showing how light passes through the lens. Science teachers can also use Jello to make lenses that will show laser light refraction.  I tried that and had disastrous results.  I started to play around with mixing baby powder (mostly cornstarch) with red food coloring and water.  I was quite pleased with the results.  Go ahead and watch the video below to see what happens.