Hands down one of my favorite resources is the AIMS Education Foundation. If you have not looked into these books, please do so, you won’t regret it! They have materials available from K- 9th grade in math and science. I don’t know anything about the science stuff, but the math ones have been some of my favorites for years. I had the opportunity to go to an AIMS training a few years ago, and as a part of the training, I received 2 free books, then I actually won 2 books while I was there. In addition, I went with a friend who also got the 2 free and won 2 herself! We were in AIMS heaven. I have also purchased several of these to use as well.
If you visit the website there are a few free sample activities if you are interested in checking their stuff out. There is also a huge list of several puzzles on the website too. You can buy their books on the site or you can purchase individual activites to download immediately.
Some of my favorite books they have:
Check it out!