It’s been a stormy summer in Minnesota, and we’ve seen more than our fair share of tornadoes.  As a kid, I was always fascinated by stories of pieces of straw from a field being driven into  wooden planks in barns and houses by the swirling winds.

With a potato, plastic drinking straws and a glass of water, we were able to see for ourselves how this could happen.  Like drinking straws, real straw is hollow and although a potato is much softer than a piece of wood, we got the picture.  I was skeptical about the experiment, but it worked!

Just soak a potato in a glass of water for about 30 minutes.  We used a red, boiling potato, because that’s what I had on hand.

Then, grasp a straw tightly, near the middle and stab it into the potato.  We were surprised to find that, instead of breaking or bending, the straw can be driven quite a way into the potato.  This happens because objects in motion, like the straw, tend to stay in motion and objects at rest, like the potato, tend to stay at rest.  This is known as inertia.  In addition, the thin edges of a drinking straw don’t offer much resistance.

Try it!

Now that it’s summer, move your science lab outside and try doing the Tablecloth Trick or Throwing Eggs.  If you’d rather check out the power of the sun, try making a solar oven from a pizza box!  You probably have everything you need for these experiments right in your kitchen, and if you don’t have a pizza box, just save one next time you order out.

What are you waiting for?  Have fun!

Imagine pieces of matter (too small to see) called atoms that will only fit together in a certain way, like a puzzle.  These atoms can attach to each other to form small three-dimensional shapes, or larger ones, but the shape will always be the same, depending on what kind of atoms make up the “puzzle pieces.”

This is what happens when crystals are formed.  Diamonds and salt, for example, are crystals shaped like cubes, while quartz crystals are formed in trigonal shapes, sort of like three-dimensional kites. You can have very small diamonds, or huge ones, like the Hope Diamond, which is as big as a silver dollar and blue from impurities in the stone, but they will all have the same basic shape.

We grew alum crystals in a jar last week and I am amazed at how beautiful they are.  I couldn’t get a very good picture, but they look like a string of real gems and were simple to grow.

To grow these spectacular crystals, you will need a small jar of alum, which can be found with the spices at the grocery store, water, a glass, a jar, a stick and some thread.

Fill the glass with about 3/4 cup of water and add a few teaspoons of alum powder.  Stir until the powder dissolves and repeat until no more alum will dissolve and you can still see some floating around in the glass.  Then, let the glass sit overnight or until some small alum crystals form in the bottom or on the sides of the cup.  It took two days for us to get some decent crystals, but we got several small ones that were fun to look at!

Fish a large crystal out of the glass with a spoon and tie a thread around it.  Tie the other end of the thread around the stick (we used a BBQ skewer) and wind it up so that you can rest the stick over the mouth of the jar and the crystal will hang down about half way.  Then, pour the remaining liquid from the cup into the jar.  There is still alum in the water, which will add more “puzzle pieces” to the crystal and make it grow bigger.

Now you can watch your crystal grow.  What shape is it?  Look at your crystals under a magnifying glass.  Take a picture of them, or draw them your science notebook!  Here is a link to a great Smithsonian website where you can learn more about gems and crystals.

Here’s a quick experiment for bored kids:

You’ll need a button, a glass, water, and a carbonated beverage.

Pour some water in the glass.  Drop the button in.  What happens?

If it sinks*, dump the water out and fill the glass with carbonated beverage.  Drop the button in.  Now what happens?

The button is more dense than the water and sinks in uncarbonated water, but in a carbonated beverage, carbon dioxide bubbles form on the button and make it buoyant, so it floats to the top.

What other sinking objects can you make float with carbonation?

If your kids like this, check out this Float or Sink experiment that even very young kids can do!

*If your button floats, the experiment won’t work, so try to find one that sinks!

It’s been raining for about two weeks straight in Minnesota and my kids are climbing the walls.  Yesterday, they built an amazing fort and played in it for an hour before they came to me asking what they could do next.

This easy experiment kept them busy for a little while.

Take a plastic comb and comb your hair a number of times, or rub it on some tissue paper.  Tiny charged particles called electrons will collect on the  comb and give it a negative charge.

Now, run a very thin stream of water from a faucet and hold the comb next to it without actually touching the water.  What happens?

The stream of water is positively charged and is attracted to the opposite (negative) charge of the comb, pulling and bending the stream of water toward the comb.

Pretty cool.

Many more experiments to follow in the next few months!  We’re planning a summer of science between our many sporting activities, so get those science notebooks ready and follow along with us!

This is a fun experiment to try outside, on the lawn, where your kids can spill as much water as they want to.   All you’ll need is a table, a sturdy, heavy glass that isn’t too tippy (we used a bar glass and it worked pretty well,)  a smooth tablecloth and water.

We used easel paper as our tablecloth, but your kids could try a plastic tablecloth or even a cloth one that doesn’t have a heavy seam on the edge.  The more slippery the tablecloth, the better it will work.  I’d also recommend bringing out a pitcher of water for refilling the glass and a towel for wiping up spills.

Have your child put the paper or tablecloth near the edge of the table (see photo above.)  Place the glass of water on the tablecloth.  I wouldn’t recommend filling it to the top.

This part is important!  Your child must pull the tablecloth straight down, along the edge of the table, very fast.  If they pull it out, toward them, or pull it too slowly, it won’t work.  If they do it correctly (and it may take a few attempts), the water will slosh a little, but the cup will remain on the table, full of water.  We spilled a lot, but had a great time.  All of the older kids involved were able to do it successfully by themselves, but I had to help my three year old a little.

The law of inertia says that objects don’t want to change how fast they’re moving (or not moving, in the case of our glass.)  They heavier something is, the more inertia it has.  In our experiment, the heavy glass of water is standing still and doesn’t want to speed up.  Since the tablecloth is moving under the glass very quickly, the heavy glass slips on it and doesn’t move very far.   It seems like magic, but it’s just physics.

On another note, I’m participating in a contest at Best Kids Apps, a blog about iPhone apps for kids, for a chance to win an iPad.  I don’t have an iPhone or iPad, but would love to have one, mostly since I’m obsessed with severe weather and would love to have Dopplar radar at my fingertips.  The iPhone/iPad also has great apps for kids books, which would be really useful for vacations, and even an app for geocaching!  I was thinking it would be cool to make a KitchenPantryScience app, so you could look up easy kids science projects wherever you are (like at the cabin on a rainy day.)

“Kids aren’t getting dirty these days. They’re not playing in the mud, not playing in rain puddles,” says Dr. Truglio, of Sesame Workshop in a Wall Street Journal article Wednesday, about getting your kids outside.

Next to the kitchen table, my back yard (or front yard) is my favorite science laboratory.  It has the added bonus of being easy to clean up.  For this fun, messy experiment, a hose and a few paper towels did the trick. 

My dad, who is a physicist, told me about this great demonstration that teaches kids a little bit about motion and force while letting them do something that they are rarely, if ever, allowed to do- throw eggs!  All you need is a sheet, some clothespins or string, raw eggs, and some paper.  You could use newspaper or easel paper.  It is just to make cleaning up easier.  I also used a portable table turned on its side as a wall, but you could just use a wall and have your child hose it off when you are finished.

Hang the sheet up from a tree, if you have one.  If you don’t have a tree, you could hang it from anything else, or have two tall children or adults hold it.  Then have two children hold the bottom of the sheet up, or tie it to chairs  so it makes a J shape when you view it from the side.  The idea is to keep the eggs from hitting the ground and breaking. 

Have your child throw a raw egg at the sheet as hard as they can.  It won’t break because the sheet slows the egg down.  The law of motion says that the faster you change speed, the greater the force.  When you change the speed of the egg slowly, like the sheet does, it lessens the force of the egg stopping and the egg remains intact.

Now, put some paper on a wall (or table like we did.)  Have your child throw the egg at the wall.  They will see what happens when something stops fast.  Once again, the law of motion rules.  When you change the speed of the egg quickly, it stops with a lot of force.  SPLAT.  My kids loved this part.  I had to stop them from using all my eggs. 

Tell them that this is one reason they put airbags in cars.  If a car is moving and hits something, causing it to stop very quickly, the airbag act like the sheet, slowing the person in the car down and greatly reducing the amount of force they might hit the dashboard with. 

Have your child record their results in their science notebook, if they want to.  They can write or draw what they did, write the word force and record how many eggs they threw and which ones broke. 

Finally, make sure they wash their hands when they’re done playing and cleaning up.  Remind them that raw eggs can have a bacteria called Salmonella living in them and on them. 

Have fun!

When my friend Sheila, who works at NREL (the National Renewable Energy Laboratory) sent me this project, I couldn’t wait to try it out.  Unfortunately, it’s spring in Minnesota.  That means it’s cool outside.  We decided to attempt the project anyway on a cool, 60-degree day and to my surprise, it worked.  The oven didn’t get very hot, but we were able to warm a chocolate chip cookie enough to make it soft and melt the chips.  We’re planning try it again on a warmer day to see what happens!  NREL suggests using your oven to make s’mores, which would be really fun.  I just didn’t have the ingredients on hand.  The solar oven is surprisingly easy to make.  I think it only took us 10 or 15 minutes, with my help.

You will need: 1 pizza box from a local pizza delivery store (Little Caesars, Domino’s, Pizza Hut, etc.), newspapers, tape, scissors, black construction paper, clear plastic wrap, aluminum foil and a dowel or stick to prop the lid up.  You will also want to have some food to warm in your oven-marshmallows, chocolate, etc.

Make sure the cardboard is folded into its box shape.   Carefully cut out 3 sides of a square in the lid of the box.  Do not cut out the fourth side of the square, which is the one closest to where the pizza box lid hinges.  Gently fold the flap back along the uncut edge to form a crease.  See photo below!

Now, Wrap the underside (inside) face of the flap that you made with aluminum foil.  Tape it so that the foil is help firmly but so that there’s not too much tape showing on the foil side of the flap. 

Open the box and place a piece of black construction paper so that it fits the bottom of the box.  Tape it by the edges. (We used two pieces.)

Roll up some newspaper and fit it around the inside edges of the box.  This is the insulation.  It should be about 1-1 ½” thick.  Use tape (or other materials you can think of) to hold the newspaper in place.  Tape it to the bottom of the box so that you can close the lid. (We taped it to the sides and had to cut the tape so that we could close the lid.  Luckily our newspaper fit in tightly enough that we didn’t really even need the tape.)

Finally, cut plastic wrap an inch larger than the lid opening on the box top.  Tape it on the underside of the lid opening.  Add another piece of plastic wrap to the top of the lid opening.  This creates a layer of air as insulation that keeps heat in the box. It also makes a window you can look through at the food you’re “cooking.”  BE SURE THE PLASTIC WRAP IS TIGHT.

You are almost done!  According to NREL, the oven needs to sit at an angle facing the sun directly so you’ll need to make a prop.  You could probably just use a book or something under the hinged side of the oven.  However, I missed this when I read the directions and we just put it flat on the ground.  The flap of the box top needs to be propped open—a dowel or ruler works great.   We used a wooden skewer that I broke the sharp point off of.  This way you can change the amount of sunlight striking the oven window.  Play with the angle of the flap to see how much sunlight you can get to reflect on the food. 

Check every once in a while to see how well your food is being heated by solar thermal energy. If you’re is interested in finding out how the sun cooked your food, go to http://www.nrel.gov/  NREL’s website has great information on solar energy and many other sources of renewable energy.

Kids from two to twenty will have fun playing with this science project.  Click here for my blog post on Tie-Dye Milk and to read more about surface tension