What size object fits through what size hole? The idea of passing items through a filter is something we adults take for granted, but can be such an interesting discovery for little ones. This filtering activities takes a bit of planning, but can be done with things you probably have around your home.
Materials: Filters of various sizes - you can use strainers, colanders, cheese cloth or other cloth. You can also make your own filters by drilling or cutting holes in cardboard or in the bottom of boxes. You also need items to filter. Choose items of different sizes that will fit through some of the filters but will get caught in others (we used: rice, corn, sugar, a pumpkin, oatmeal, nuts, gourds, and couscous).
This discover challenge does take a bit more set up and structure. There are many ways you can do this challenge, but it seemed to work best to do one item at a time. Start with the largest filter and pass each item through the filter to see what gets filtered out. Work your way through all the items and all the filters, noting what items pass through which filter.
Next combine all the items into one bowl, and filter out the different items by passing them through each filter from biggest to smallest. By the time you get to the last filter, you should have only the smallest item(s) filtered out. It is also interesting to run a liquid through the filters at the end to demonstrate that some things go through all filters.
Truthfully, it took a little work to take turns and pass each item through each filter, but eventually we got the hang of it. They were pretty amazed that we were able to combine all the items and filter out the sugar - it seemed to appear from nowhere. Of course there was some dumping at the end, and the inevitable pile of rice on the pumpkin.
The sign of a great discovery, a complete mess!