AIMS Education Foundation is an organization aimed at giving students a solid understanding of math and science.
For awhile I maintained a subscription to their magazine. It's a beautiful, high-quality publication. I did let my subscription lapse... I found it to be a bit expensive and I felt like there were more lessons geared toward math than science in the editions I received (that may have just been a function of that particular year, or just something I imagined, but regardless, it just wasn't meeting my expectations). However, I do know that they have produced some great activities, that I've come across through other resources (and thus my interest in the magazine).
Even if you're not interested in the AIMS publications... head to their website - they have several of the activities available as free samples. There aren't a lot, but you might find something of use to you.
There are also some downloadable activities that are available for a dollar or two each.