See 2 video demonstrations of diffusion in action. The first video shows a drop of food coloring diffusing through water. It is a video that is time lapsed at 1 frame/15 seconds. The second video shows a Ziploc bag of iodine placed into a beaker of starch water. It is a video that is time lapsed at 1 frame/30 seconds. The iodine diffuses out of the bag and into the starch water. Where the iodine is diffusing the starch water turns a dark blue.
This video clip shows 7 demonstrations of Newton’s first law of motion–the law of inertia. Newton’s law of inertia states that objects moving at constant velocity will continue moving at constant velocity, unless acted upon by an outside unbalanced force. Six of these demonstrations (excluding demo 6) are from Tik Liem’s book Invitations to Science Inquiry. I have students volunteer to do all demos, except demo 5. All of the students in class receive a handout that they must fill in so that they understand how inertia is demonstrated and all the forces that are involved.
Signs of a chemical reaction include color change, gas production, temperature change, precipitation, and other changes in properties …including density, taste, texture, smell, melting point, boiling point, etc. This demonstration will really make them think about it. Place a large plastic container on the counter. Invert a large jar or beaker into the container. Set a 3/4 full liter of fresh cola on top. Carefully but quickly pour a cupful of sugar into the soda and stand back. The cola will burst out of the bottle. Most students will assume it is a gas production sense they can see all of the foam. Have the students taste the left over soda. It is very sweet and very flat, indicating the soda is still there and the carbon dioxide left. It is a physical change and not a chemical change. The sugar pushes out all of the carbon dioxide gas.
After using an old version of the Wordpress blog engine, I have decided to scrap the whole site and start over. I don't have the right skill set to successfully use Wordpress and keep it up to date, so I am moving to Squarespace.com. I have such an old version of Wordpress that I can't export my posts and import them into Squarespace. So over the summer I am going to post all of my old entries one at a time to the new site. For those that have been using my site over the years, I want to thank you and bear with me in this big transition. Hopefully as a result, I will be more motivated to post in the future. Thanks!