This is a really easy kid activity to go with Leo Lionni's Little Blue and Little Yellow, (affiliate link) a delightful book about color mixing.
It's so easy you don't really need much in the way of instructions. All I did was cut a few cellophane shapes out of blue and yellow cellophane which Kiddo played around with as he followed along with the story.
Once he had the shapes, he even used them to tell the story to himself while I was busy with other things.
Best of all, this is a no-mess activity!
More color fun:
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