Teach Engineering is designed for teaching sciences and applications to younger than college-age students, but there are some wonderful experiments and activities described here for anyone and everyone, which even include bibliographies. There is a very nice Environmental History Timeline, and there are lots of environmentally-appropriate projects/studies included, especially in the Chemistry, and Earth and Space, Life Sciences, and Physical Science. Or most seem to be under Science & Technology details, too. Click on Browse Curriculum, then subjects to get the details of the lessons and activities.