How many drops of water can fit on a coin before it spills? Part of a 20-challenge series, students are amazed as they discover the power of surface tension in this simple but thrilling science challenge! Using just a coin, a dropper (or straw), and water, children carefully count drops, make predictions, and observe how water molecules stick together to form a dome shape. This activity introduces the concept of surface tension and cohesion with a real-world connection to how water behaves in na