what about sink and float experiments comparing different objects to see ho long it takes them to sink?
I used to do fruit. One group got apples, one got oranges. We would then fill out a venn diagram comparing/contrasting apples & oranges.
My college english professor made each of us bring in a dozen cookies and then we each picked a certain number of cookies and had to write an essay comparing and contrasting the cookies. Could you do something similar? The differentiation could be in the product: some students might complete a Venn diagram and write one sentence, some might complete the diagram then write 3-5 sentences, etc. Depending on ability, you might have sentence frames already made and students only have to fill in one word.
I have the kids do a venn diagram and compare and contrast each other. Working in groups of two. Its fun and they learn new things about each other.