I want to introduce the concept of soluble and insoluble to my preschoolers ages 3 and 4 ...
What experiment could I do with them so give them a better understand of items or materials that are soluble and insoluble?
This works quite well with rock salt (so big lumps) and water to demonstrate soluble and say un-cooked coarse ground rice or a small grained rice to demonstrate insoluble. They can taste a little of the salty solution to see it is saltly.
Then have a mixture of the two, pour into water and stir for a few minutes. Use a sieve to filter and recover the rice. Then allow them to taste the liquid (filtrate) which is salty. You can also demonstrate that you can recover the salt by allowing a small amount of the solution to evaporate overnight.