Category Archives: Experiments With Kids

Aquaponics

We recently set up a new fish tank.  It’s the Back to the Roots Water Farm.  It’s really neat.  Our betta fish, Toodles, lives in the water (because, where else would a fish live?).  On top, we can grow plants.  Right now, I’ve got either lettuce, spinach, or Swiss chard.  I can’t remember what seeds I added.

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Toodles.

There is a pump in the tank to bring water up to the growing surface.  The nitrogenous fish waste provides food for the plants.  The plants remove the harmful nitrogen compounds from the water.

It’s billed as a self-cleaning tank.   I’m not convinced that my little plants can handle all of Toodles’ waste yet, so I change about 25% of the water once a week or so.  The other problem we’ve encountered is algae.  Algae grows when the water is exposed to lots of sunlight.  Sunlight is required for my plants to grow, so I can’t just put it someplace dark.  We added a snail, which my daughter named Cinderella.  True to her name, Cinderella the snail works hard to help remove the algae and keep the tank clean.

My daughter has been fascinated watching the plants grow.  We put seeds in, and now we’re getting some sprouts.  She’s really trying to understand how all this is happening, and it’s been a fun way to explore science with her.

The tank holds about 3 gallons.  It’s much nicer than many betta setups, because it is so spacious.  The only addition we have is a heater, since betta are tropical fish.  Toodles is one happy, active, fun fish.  Our family is enjoying watching him and learning from him.

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See my beautiful sprouts?

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Blowing Up Balloons with Yeast

Yeast are amazingly talented little organisms.  They make bread, beer, wine, certain dairy products.  Did you know that yeast can also blow up balloons?

 

Here’s another fun experiment to do with the kids:

 

Find a small bottle, like a soda or water bottle.  The smaller the bottle, the better your results will be.

Fill the bottle about 1/2 to 3/4 full of warm water.  It should be about the temperature of nice, warm bath water.  If the water is too cold, this will take a long time.  If it’s too warm, it will kill the yeast.

Add some yeast and some sugar (about a tablespoon-ish of each).  Quickly stretch a balloon over the mouth of the bottle, and make it air-tight with some masking tape.  Give the bottle a bit of a splash/shake to help mix it up, and watch and see what happens.  After juts a few minutes, you should see the balloon start to fill up a bit.

 

What’s happening with this?

Well, the yeast is breaking down the sugar, and using it to get energy.  One of the by-products of this process is Carbon Dioxide.  The Carbon Dioxide is released by the yeast, and fills up the balloon.  That’s also how yeast helps bread rise- by producing air bubbles in the dough.

C UR DNA (See your DNA)

Have you ever wanted to see your own DNA?  It’s actually pretty easy.  Seriously.  You can do it right now with stuff you normally have at home.  Here’s a link for the instructions:

http://www.pbs.org/wgbh/nova/body/extract-your-dna.html

 

This is fun to do with older kids.  You can explain how that gooey stuff contains all the information for making them how they are.  Or just enjoy seeing something that normally seems so unimaginably small.