I think kids would have a blast doing this especially if they got to climb somewhere and drop the marble from really high up. Good opportunity for kids to try science practices like note taking, measuring and wearing goggles. I personally struggled doing this because I did not want to sacrifice my good four or coco powder for science. I know marbles are pretty popular right now with kids, so many of them would possibly have different sized marbles, but I did not. I’m wondering if kids have small sized bouncy balls or if even coins would work similarly enough to do this project. That could be part of the experimenting. Once kids are done measuring their craters and making scientific observations with what kind of impact round objects make they can try other shaped objects and see if the craters are different. Maybe they can reenact the first moon walk with their toys. Speculate earths craters and why the might be the same/different.