🪐 Build a Planet Model – Density Test STEM A Hands-On Space Science Experiment for Kindergarten–Grade 2Make space science exciting with this fun 14-page STEM activity where students explore the concept of density by designing and testing their own planet models! In this hands-on experiment, students predict, build, and test whether their “planet” will float or sink in water, helping them understand how density affects objects. Students also learn basic space science concepts and discover