Exploration Education Science Curriculum

Science Activity
"It's Needling Me "

Materials needed:

1 sewing needle
Paper
Bowl of water

Instructions
Step 1 Take a sewing needle and set it down on top of the water in the bowl. What happened?
Step 2 Okay -- the needle sank. Of course metal cannot float on water, or can it? This time, first float a small piece of paper (larger than the needle) on the water and gently set the needle on top. Carefully press down on the sides of the paper so that they get water logged and the paper sinks (or you can just wait - it will sink eventually).
What happened? You should have found that the needle remained floating on the surface. So how can metal float on water? First, we need to understand that water has a certain amount of tension (type of force) on its surface. It is not too strong, but this is why a water strider (water insect) can run across the surface and not sink. This tension is there because water molecules are attracted to each other. This attraction is strong enough to keep light objects (needles and water bugs) from breaking through.
Explore further Can you get the needle to float by holding it parallel to the water (almost touching it) and then dropping it? How about lowering it down gently with a fork? The key is that the entire needle must hit the water at the same time, not one end before the other.