Materials Needed:

  • Large mixing bowl or container (a casserole  pan would work!)
  • Plastic bag (I recommend quart size) filled ¾ of the way with water
  • A bunch of pencils or colored pencils--the sharper the better! 

Directions (prep):

  • Fill your plastic bag ¾ of the way with water 
    • You may want to fill a few because this experiment is very fun!
  • Sharpen your pencils
  • Prep the activity area with the bowl or casserole pan

Directions (activity):

  • Ask your young scientists if they think you can poke a pencil through a bag of water without spilling a drop (they will probably say “No way!”)
  • Hold the bag up over the bowl or other container
  • Carefully twist a pencil through one side of the plastic bag and then continue to twist through the other side
  • No water will spill!
  • Try it with the other pencils

Invite your young scientists to try on their own using bags of water and pencils

The Science:

  • Plastic bags are made of something called a polymer
  • Polymers have long strings of molecules that are flexible
  • When you poke the pencil through the plastic bag, it wiggles in between these strings of molecules and the molecules seal up around the pencil so that no water is spilled!

Extend the learning:

  • Spend some time looking on the internet for other household items that are polymers - you’ll be surprised by what you find!