Puncturing a bag full of water.

If we puncture a bag full of water and leave the pencil in the hole, will the water spill out?

No. Plastic is a polymer made of long, elastic molecules. When the pencil punctures the bag, these molecules form a hermetic seal around the area where the pencil is inserted. This polymer seal prevents the bag from dripping. When we remove the pencil we “break” this seal and that is why the bag begins to drip.

During the Covid19 crisis, while school was closed, we’ve have tried to keep STEM working. In the groups of small pupils (3 and 4 years old) teachers have recorded videos with STEM challenges and send them to the families so that they could do small scientific investigations with materials that they had at home. We've collaborate with families and some of them even have recorded their own videos showing us the results.