If your kids are anything like mine, they eat a lot, and so I find myself in the kitchen a lot. Invariably, they follow me in there (“Mommy, what are you doing? Mommy, can I see? Mommy mommy mommy mommy…”), and so I thought, what about setting up some science things for them to do in the kitchen? Here are my 10 favorite ones. Note: many of them may be messy. We like mess in my house, but you may want to put down extra plastic tablecloths/tarps before you begin.
1. Volcanoes: Baking soda and vinegar release carbon dioxide and make a volcano-type explosion. Food coloring can make a colored volcano, and a few drops of dish soap can make it extra bubbly and explosive!
2. Lava Lamps: Lava lamps work on the principle that oil and water don’t mix in general, because of the differences in their density (and other structural properties), but that we can change the relative densities by adding salt to the mixture. Add food coloring to the water, oil on top, and then put salt in to watch the layers mix. Note that this also works well with an alka-seltzer tablet for many of the same effects.
3. Oobleck: Mix corn starch and water to get a substance, called Oobleck, that is an example of a Non-Newtonian fluid. This means that it acts as a solid when you put pressure on it (like squeezing in your hand), but turns liquid without that pressure. Play with the consistency by varying the corn starch/water ratios, and have fun making a big mess!
4. Milk Painting: This works best with whole milk because it has a high fat content.Put some whole milk on a plate, and then add a few drops of food coloring to the center. The food coloring will not distribute, because it does not like the high fat of the milk. Add a few drops of dish soap on top of the coloring though, and that emulsifies the fat and lets the colors mix through the milk to generate a beautiful “painting.”
5. Plastic Milk: If you mix milk and vinegar, it turns into a substance with a plastic-like consistency. Why? The acid from the vinegar reacts with the protein in milk to cause the protein to come out of the solution and form blobs. Why does acid do that? Chemically, it protonates many of the residues on the protein, which turns the structure from hydrophobic to hydrophilic, but that may be more information than you are looking for. The blobs will have a fun, plastic-like consistency. Check out more details on this website: https://sciencebob.com/make-plastic-milk/. This also works best with whole milk, because the environment in the whole milk is the most hydrophobic and so drives the protein out of solution quickest.
Also note: if you have a child with dairy allergies (I do!), I have not tested these experiments with soy or almond milk, and I am not sure that they will work well under those circumstances. We have been giving my child plastic gloves to wear while he does the dairy experiments, and that seems to work pretty well for us.