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Remote Ready Biology Learning Activities has 50 remote-ready activities, which work for either your classroom or remote teaching.
Weighty Problems
The following is from Wikipedia on the anomilies of gravity.
I don't claim to understand much of this, but I have been following the debate on the nature of Dark Matter and the expansion of the universe.
There are some observations that are not adequately accounted for, which may point to the need for better theories of gravity or perhaps be explained in other ways.