Whole class science fair projects are a fun way to work together as a class to solve a problem. These class projects can look at big science issues like global warming, or simple science concepts like solubility. No matter what your class decides to do, remember that the project is a team effort and that all students need to participate equally.
The first option that you have for whole class science fair projects is to explore simple subjects like solubility. A fun project is to use solubility to separate solutions into pure elements. One experiment is to use solubility to separate salt from a salt and pepper mixture. This experiment will steep the salt and pepper crystals in boiling water. Since salt is water soluble and pepper isn't you will be able to strain out the pepper crystals with a coffee filter.
Another option that you have for whole class science fair projects is to experiment with temperature. Chemistry science experiments that you can complete include using water of different temperatures to dissolve Alka-Seltzer (R) tablets. Your job will be to determine if the temperature of the water affects how fast the tablets dissolve or react to the water. You can get the whole class involved in this experiment by assigning one temperature of water to each team of students. You can then combine your results and work together to analyze your data.
Magnets are so much fun! Kids can have a real hands-on experience going around the room and seeing what is magnetic. For the younger students you can give them a picture bingo card with pictures of objects that will and will not attract magnets. The first one to get "Magnetic Bingo" can win a special privilege. For the older children, they can draw their own images on a card or make a chart. To demonstrate magnets here are two classroom demo kits
If you are interested in chemistry science fair projects then consider chemical reaction experiments. These experiments can look at just about any type of chemical reaction you are interested in from reactions that cause small scale explosions to reactions that cause a physical change to the test materials.
To get the whole class involved in these experiments you can split your class up into teams and have each team complete the experiment. Then you can compare the results that each team got. Explain why the results were the same or different.
For a simple project that the whole class can complete together consider candy chromatography. For this class experiment you can give each student a different type of candy, for example, chocolate, M&Ms, Reece's Pieces, etc. Each student will then moisten the candy and rub it on a piece of chromatography paper. As the colored fluid is drawn up the chromatography paper you will notice what colors were used to make up the candy's shell. Compare the different die combinations used to create similar colors by different candy companies.
Getting an entire class working on a single project is not easy to do. However, if you are successful at doing this, you will not only make science more interesting for more kids, but you will also find that you can tackle more complex science concepts when more people are involved. This will teach students the importance of collaboration in the professional realm of science. Have fun with your experiments!