In this hands-on STEM challenge, students design and test a film canister “submarine” that sinks as slowly as possible. By exploring the relationship between mass, volume, and density, students will learn why some objects float, sink, or hover in water. This activity is perfect for middle school physical science or as an NGSS-aligned enrichment lesson on density and buoyancy. Students love the challenge aspect, and teachers love the ready-to-use directions, data tables, and answer keys! Wh