One of them is this box which can be used for distinguishing colors and fine motor development for toddlers. Originally, it was just an empty box of cornflakes, which I turned upside down, poked some holes in it (that was the hardest part because I didn't have a scalpel) and decorated them with some washi tape. As we were out of a blue tape, the Younger simply colored it:
We collected many bottle caps, in various colors and started sorting it:
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However, in the end, the girls really enjoyed in simple mess making: