Why do some materials float on water while others sink?

🧠 Detailed Explanation (For Older Kids)

When something floats on water, it means it's less dense than water, which is a way of saying it's lighter for its size. For example, a big, heavy rock sinks because it's dense, but a hollow plastic bottle floats! This happens because the water pushes up on the materials, trying to keep them afloat. So, next time you're at the pool, think about why your rubber duck stays on top while a stone doesn't!