Geek Mama Science Snack: The Self-Healing Baggie

CVR Mama Gone Geek_Roost Books (2) (1)Wow your kids with science! Try this idea from the “Mama Gone Geek” author Lynn Brunelle…

Kids back from school. Clamoring for a snack? Here’s a fun activity to feed their noodles while they nosh and nibble. All you need for this amazing trick is a Ziploc baggie, some sharp pencils and some water.

It’s a perfect after school activity to do with a pencil and that baggie you put your sandwich in.
The challenge?
Poke a hole in a bag full of water and don’t spill a drop.
Think you can’t?
Well, you CAN!
It’s an awesome way of playing with the chemistry of polymers.
Seriously. It’s way more fun than it sounds.

Practice this amazing experiment (over the sink, or outside) before you use it to dazzle your audiences.

Leakproof BaggieWhat You Need

  • A Ziploc baggie
    (it doesn’t matter what size as long as it seals)
  • Water
  • Several sharp pencils

What You Do

    1. Pour water into the Ziploc baggie. Fill it anywhere from ½ to ¾ full.
    2. Zip it.
    3. Hold the bag in one hand from the top.
    4. With your free hand, grab your first sharp pencil and poke it through one wall of the bag, through the water and out the other side.
    5. Make sure you have pencil sticking out of both sides of the bag. If not there will be a mess.
    6. Any leaks? There shouldn’t be one.
    7. Once you get the hang of it, try it with a flourish and hang the bag over some unsuspecting friend’s head. As them what will happen.
    8. Instill fear.
    9. Then perform the scientific feat of amazement.
    10. Jab more and more pencils into the bag.
    11. When you’re done, hold the bag over the sink before you take any pencils out. Once you do the bag will leak. A LOT!

What’s Going On? – What’s the Science behind the Fun?
It’s not magic, it’s SCIENCE! It’s all about polymers.

Polymers are long chains of molecules the make up plastic. Plastic bags are made up of lots of long polymers. It’s what makes baggies so stretchy. When you jab a sharp pencil through the wall of the bag, the polymer strands move around so the pencil can slip through. These long chains then wrap back around the pencil making a seal that holds tight—keeping the water in.
Pull the pencil out and you have what scientists call—a big hole. The water will pour out.

Try it!

Lynn BrunelleLynn Brunelle is a four-time Emmy Award-winning writer for the television series “Bill Nye the Science Guy,” with over twenty years of writing and teaching experience. She is the instructor for our Aloha to Summer camp program as well as an author of multiple books, including “Pop Bottle Science” (available at the KiDiMu Gift Store). She is also a regular presenter of art and science projects in classrooms and public events.