This is a combination of two of my favorite scavenger hunts complete with grading rubrics.
The first one requires a good bit of time, some simple research and care since students are collecting live specimens. They can collect a variety of specimen such as "a yellow wildflower" or "lepidoptera." You can have them catch and release them with digital evidence or have them bring them in to you for verification. I used it as a final exam grade in biology and the kids loved it. I suggest you modify it for the season and your location. I left it as a word doc so you could modify what you needed.
The second one is all digital and can be done in just a few class periods. It covers cycles, webs, trophic levels and relationships and allows for an easy classroom presentation of their evidence. Grading is easy as I included rubrics for each scavenger hunt.
These are very popular, fun for the students, easy to do, and cover a lot of material. Enjoy!