Don't be put off by the word engineering in this site - it's actually a great science website with lessons and activities for all ages.
There are dozens of units on topics ranging from the pyramids to bone density.
Each unit has an overview that links to the lessons and activities that go with it.
Whether you search or browse, the table of results lists the relevant units by title with a summary, the grade level, and details about the curriculum.
There is no fee or registration required to use the site, but if you want to register (it's free),
you can take advantage of MyTE, which is a personal account where you can store your favorite units and write and submit reviews on it.
The site was created with funding from the National Science Foundation.
"Engineering faculty, graduate and undergraduate students, and K-12 teachers were key participants in this endeavor.
Each institution had local school district partners engaged to promote engineering as a vehicle f or math and science integration as they developed and classroom tested the curricular materials.
The resulting lessons and activities relate to everyday encounters in the lives of youngsters, thus providing an engineering context for student learning."