I love google forms! I have done tons of assessments using forms, gathered feedback, used it to create groups based on student choices, and more. It's a fantastic platform that can fill many needs.
Number Sense Routines have become my passion. Over the past couple of years, I've been exposed to more and more websites with so many free resources. Now, I am obsessed! There is so much variety. I love how these routines and puzzles teach students so many skills. Most of these could be used in an online environment, so no matter how you're teaching this year, these will work for you!
Google Slides are great for Collaborative Work! Think about collaborative story writing, number sense routine discussions, jigsaw reading, and more! See my periodic table project for one such idea.