I love doing hands on scinece projects with my students. Anything that involves multiple materials that are easy to manipulate, colorful and fun, and mimic real-life situations they see in their own community. For example, I did a lesson on living and non-living things. We had students observe and write down characteristics of a gummy worm. Then, they got to observe and handle a real-life earthworm. The students LOVED it.
Another activity I would reccomend for older elementary would be having them plant their own seed garden. This can help them start to think about the water cycle, plants and how they grow, and observation techniques.