School’s out and the pressure’s on to engage your science-y sidekick this summer—it’s time to bust out simple experiments that reveal air’s invisible power. We’ve rounded up 10 air pressure experiments that seem more like unexplained phenomenon than hard core science. If your kiddo didn’t think you had magical powers before, she will now!
photo: Allison Sutcliffe
Keep it Simple
Thankfully, science doesn’t have to be super complex or time consuming. These easy-peasy experiments only require a little prep and leave a big impression on tiny minds. Plus, we’re betting most of what you need to test these theories is already lying around your house.
1. Sink or Swim. Instead of bobbing for apples, your tiny tot will make straws dive and surface with a gentle squeeze. The Kids Activities Blog lays out the important deets for this hands-on experiment that uses a two-liter bottle and play dough to fully certify straws as scuba-ready. Take the dive into serious science with this one!
Why it works: Squeezing the bottle increases the air pressure inside the bottle and forces water up into the straw, which makes it heavy enough to sink.
photo: Allison Sutcliffe
2. Blow Their Minds. Bet your cutie a clean room that she can’t blow a rolled up piece of paper towel into an empty bottle. Sounds like a safe bet, right? But thanks to air pressure, the cards are definitely stacked in your favor. To set up the experiment, place an empty two-liter bottle on its side. Ball up the corner of a paper towel that’s about half the size of the bottle’s top and place it just inside the opening then challenge your little scientist to blow the paper towel into the bottle (Trust us, it can’t be done). No matter how hard she tries, she’s not going to win that bet. Learning plus a clean room? We’ll take it!
Why it works: Even though you can’t see it, that bottle is full of air; when you try to blow something into it, there’s just no room.
3. Be Unpredictable. Two balloons, a yardstick, string, and a hairdryer are all you need for this experiment that will keep your mini me guessing. To get things moving in the right direction, blow up the balloons to the same size and then use the string to attach them, a few inches apart, to the yardstick. Once you’re all set up, ask your kidlet what will happen to the balloons when you aim air from the hair dryer between the two balloons. The obvious answer? They’ll be blown apart. But once your wee one takes aim, she’ll see that the balloons are actually pushed together rather than apart. Who knew?
Why it works: Blowing air between the balloons lowers the air pressure and makes the pressure surrounding them higher, pushing them together.
photo: Allison Sutcliffe
4. Levitate Water. You won’t need to incant Wingardium Leviosa with perfect pronunciation to suspend water during this exciting experiment. Start by filling a glass of water about 1/3 full, then cover it with a piece of cardstock. Tip the glass over, keeping the cardstock in place with your hand, and hold the whole shebang over your unsuspecting kidlet’s head (or a sink if you want to do a test run first!). Then slowly let go of the cardstock while your mini me waits excitedly below. Look ma, no splash! The card stays in place and your little guinea pig stays dry.
Why it works: The outside air pressure working against the cardstock is greater than the weight of the water in the glass.
photo: Allison Sutcliffe
5. Grab a Tissue. To be wet or not to be wet is the question answered in this simple experiment full of drama. To set the scene, loosely crumple a tissue so that when you stick it in a small glass and turn it over the tissue doesn’t fall out. Then, have your little lab assistant fill a bowl with water, turn the glass over and submerge it completely (psst… keep the glass parallel to the water to make the experiment work). Ta da! The tissue stays dry even when it’s below the water line.
Why it works: The air pressure inside the glass is strong enough to keep the water out and the tissue dry.
photo: Wesley Fryer via fli
Get mom or dad in on the action with these experiments that take a little more time and some helping hands to demonstrate just how powerful air pressure can be.
6. Blast Off. Nothing makes air pressure more tangible than a classic bottle rocket launched on a sunny summer afternoon. You and your sidekick can spend time fashioning a plastic bottle into a space-worthy vessel with a cone top and flamboyant fins on the side. Then, hook it up to the air pump and let her rip! Up, up and away! Science Sparks has simple instructions you can use (and even a cool video!) to make one with your budding scientist.
Why it works: Pumping air into the bottle builds up pressure until you just can’t add any more and all that force sends the rocket flying.
photo: AJ via flickr
7. Make Eggs Magical. This “look ma, no hands, wires or mirrors” trick will get them every time; an egg being sucked into a jar while your little scientist delightedly looks on is always a hit. To perform this illusory feat, you’ll need a glass jar with an opening just smaller than an egg (think: old school milk jar) and of course, a peeled, boiled egg. When you and your Little have checked these items off your list, it’s time to start the show. Mom or dad should toss a lit match into the glass jar, followed by your mini lab assistant, who’ll quickly set the egg over the opening. Abracadabra! Alakazam! The match dies out; the egg gets (seemingly) inexplicably sucked into the bottle. And just like that you’ve performed another bit of parent magic without breaking a sweat.
Why it works: The match uses up the air inside the bottle. Once that happens the pressure outside the bottle is greater and pushes the egg down into the bottle.
8. Build a Barometer. The invisible air pressure around us is always changing, but try explaining that to the tot lot. We’ve found a seeing-is-believing DIY barometer experiment to turn the tides for your tiny skeptic. Not only will you reveal ever-changing air pressure, but you can also predict any summer storms heading your way. Get all you need to know about making your own version using a screw-top jar, rubber bands and a straw at Wonderful Engineering.
Why it works: When the air pressure is high, it pushes down on the straw tilting it up, and when it’s low, pressure inside the jar pushes up against the straw pointing it down.
photo: Ruth Hartnup via flickr
9. Inflate Marshmallows. Put those marshmallows you’re stockpiling for summer s’mores to good use in this DIY vacuum experiment. To make the vacuum, use a hammer and nail to pierce a hole (big enough to fit a straw) into the lid of a screw-top glass jar. Next, stick a straw ever-so-slightly into the hole and seal the edges with play dough or molding clay so there’s no way for the air to get out other than through that straw. Now you’re ready to see what happens to a marshmallow when it’s trapped inside; place the marshmallow in the jar, screw the top back on, and have your mini me take the air out gulp by gulp through the straw (just be sure to cover the straw hole between breaths so no air makes it back in). As the air is removed, the marshmallow expands, like a nightmare vision straight out of Ghostbusters. Who you gonna call?
Why it works: When you use a straw to remove all the air from the jar, there’s no air left working against the marshmallow. Instead, the air trapped inside the marshmallow is able to expand.
10. Pit Balloons Against Bottles. Is your future scientist ready for another challenge? Just like blowing a paper towel into a jug, this experiment from Steve Spangler Science is oh-so-much harder than it looks. To entice your little experimenter, place an un-inflated balloon into an empty plastic bottle and ask him if he thinks he can blow it up. Easy right? But no matter how hard he tries, that balloon just won’t fill with air! The trick to inflating the balloon is a simple one that takes mom or dad’s helping hand and just like that, what was once impossible becomes possible!
Why it works: At first, the bottle is full of air so there’s no room for the balloon to expand when you try to blow it up. But when you try this experiment after the trick, there’s an escape route for the air inside the bottle, leaving room for the balloon to inflate.
Are you going to try any of these air pressure experiments with your kids? Tell us how it goes in a comment.