Math Olympics is a great project to do by grade levels or as a whole school. I have done it before and the students absolutely love participating in it. In this packet there are some suggested activities. I like these but I would also think about the CCSS and add activities from each domain. So for example, I might have a word problem challenge. In this game the students would have to sort 10 word problems into the correct category (addition, subtraction, compare, part part whole or multiplication or division).
I might also have the Polygon Race. In this game students would get 5 task cards with descriptions of 3-d figures and they would have to make all the figures out of playdoh in 5 minutes flat.
Another example would be to have a set of mixed up numbers and the students have to run and put them in order (by skip counting patterns).
Email me some of your ideas! Definitely do a Spring Math Olympics! It’s fun, engaging and academically rigorous!