Holding up the water

1. Drape a peice of cloth (e.g., a handkerchief) over the mouth of the glass or plastic container.
2. Now pour water slowly over the cloth. Water should go though the cloth and start filling the glass. Stop when the glass is half to 2/3rds full.
3. Point out to your child how the cloth is permeable and has let water through. Now pull the handkerchief as tightly as you can. Use a rubberband to hold the taut piece of cloth on the glass.
4. Turn the glass upside down. It is better to do this over the sink in case the activity didn't proceed as it should. Your child might find it surprising that the  handkerchief doesn't appear to be porous anymore.