Lemon battery

This all-natural lemon battery can power a small clock or LED. It's just one of many great at-home science experiments parents can easily do with their small children.


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When the cold and snow settles in for the winter, so begins the challenge of how to entertain your kids indoors for long stretches of time.

Well, if you've got baking powder, a couple of lemons, a magnet, a balloon and straw, you've got all you need for some snowy day science experiments — no fancy chemistry sets necessary.

Lynne Brunelle, an Emmy Award-winning TV writer for Bill Nye the Science Guy and author of the new book, Mama Gone Geek: Calling on My Inner Science Nerd to Navigate the Ups and Downs of Parenthood, is a veteran of at-home experiments.

“As you're going through the day, the more you get your kids to wonder about things, the more you get them amazed by the things in the world [and] that’s the basis of science," Brunelle says. "You’re observing, you're experimenting, you're failing, you're laughing, you're figuring it out, and that is really what science is about.”

Mike Adamick, a writer, stay-at-home dad and author of Dad's Book of Awesome Science Experiments, says he was motivated by the endless questions from his 8-year-old daughter. “Our science experiments are just kitchen sink science experiments that come from the questions that develop throughout the day, whether at home, or on a walk,” he says. “It’s just us wanting to explore the world around us.”

Brunelle says parents who are not naturally as “geek-enabled” as others, often mistakenly think they have to be a science whiz in order to do fun experiments with their kids.

“Honestly, we're all stumbling through. We're all trying to figure it out ourselves,” she says. “So I think that the greatest gift you can give to your kids is saying, ‘Gosh I don't know, let's figure it out. Let's look it up.’”

Enjoy the freedom to make mistakes, Adamick advises. “Kids don't care: they just want to get their hands dirty, have fun, and answer their questions. ... If you're not making mistakes, you're doing something wrong.”

Here are a few of their favorite things to try at home:

The straw rocket blaster

You need string, some tape, a drinking straw, and a balloon. Take one end of the string and tie it to something solid and fixed, like a chair or a door handle. Then thread the other end of the string through your straw and tie it to another chair or handle at least 10 feet away. Make sure the string is taut. Now blow up the balloon, pinching the opening closed with your finger. Tape the straw to the balloon and slide the blown-up balloon along the string until the opening of the balloon is at one end and the rounded part faces the long line of string.

When you let the air out of the ballon, it will shoot like a rocket along the line of string to the other end. “Kids just love this!” Adamick says. “There are so many variables you can do. You can tie the string up a staircase to make it go higher; you can tie it to a tree limb outside, you can tape weights to the balloon to make your rocket carry a pay load. It's just really a fascinating thing.”

The lemon-powered clock

For this, you need galvanized nails, a couple of copper pennies, some copper wire, and a juicy lemon. Stick a nail into one side of the lemon and a copper penny into the opposite side (you may need to cut a small slit into the peel first). These are now natural battery terminals.

Why? Galvanized nails are covered with zinc. The zinc atoms are drawn toward the copper, creating an electron flow through the lemon from the nail to the penny. Now tie copper wire to the penny and another to the nail, leaving the ends free. Attach the ends of these wires to the correct terminals of a small battery-powered clock and you may have enough voltage to power it. If not, use two or more lemons, putting a nail in one and a penny in the other, connected with additional copper wire. This will increase the voltage. In fact, the more lemons you link together the more power you will get.

For supervised science fun, nothing beats dry ice

It's readily available at most grocery stores, but in some areas you must be at least 18 years old to purchase it. The most commonly known thing to try is to simply drop a small piece of dry ice into a small beaker or glass of water. This is what you usually see in movies when they create a “spooky” broth or formula. For added fun, you can add dye or bubbles to the water.

If you can get ahold of old film canisters, try putting a little piece of dry ice inside one with some water. Eventually, the mixture will pop the top off.

Another variation: Put warm water and dishwashing liquid in a Pryex bowl. Get a small cloth, wet it and use the cloth to wet the lip of the bowl. Put in the dry ice and then take your wet soapy cloth and scrape it across the bowl, which should create a soapy film. You should get a really large bubble that fills with smoke.

The old standby: the baking soda and vinegar volcano

People usually put the baking soda in first and then pour vinegar on it to make an explosion. But you can also do it this way: first pour the vinegar into a tall glass or beaker, then wrap the baking soda in toilet paper, put a string around it and drop it into the beaker. Now you’ve got a little extra time before the vinegar eats away at the toilet paper and gets the baking soda wet. It's kind of a timed explosion of your volcano.

Snowflake fun

Take a piece of black construction paper or velvet outside, catch some snowflakes and look at them with a magnifying glass. You will really be able to see the crystals.

If you have a microscope slide, bring it outside, keeping it under cover, and spray it with hairspray. Catch a snowflake on it and bring the slide back under cover. Then let it sit in a cold, protected place, like a garage. You will be able to preserve the shadow of that snowflake forever, because it will make an impression in the hairspray. As the hairspray dries and the water evaporates, you get an “echo” of the snowflake.

Frozen bubbles are awesome!

In cold weather, bubbles don’t burst, they freeze, and bounce. You can actually hear them "clink" on the ground. The bubbles are a several-molecule thin layer of water, and they freeze instantly in the cold.

”Ping ping ping ping ping!”

This story is based on an interview that aired on PRI's Science Friday with Ira Flatow

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