Materials:
A plastic bag with airtight seal.
Sharp pencils
Water
Absorbent paper
Instructions:
Gather the group and ask them what they think will happen if you go through a bag with the pen. It is normal for everyone to respond that the bag will burst or that the water will escape through the hole.
Then he crosses the bag with a good and firm pulse and leaves those present surprised. You can do over your head to make children go crazy and laugh.
It crosses the bag many times and allows children to participate. At the end, remove the pencils and let the water escape.
Because it happens?
Explain that the bags are composed of polymers, which are long molecular chains that together form a surface. When you cross them with a sharp pencil, what you are doing on a microscopic scale is to separate them but without breaking them, so they remain tight around the pencil. However, this material has no memory, so it is not able to come together when the pencil is removed and the water escapes.
You can repeat the experiment with other materials such as balloons, paper bags and others so that the children understand that each material has different properties.
