Thursday, August 7, 2014

Water Power

The dog days of summer are upon us. We have been playing in water of one form or another every single day. There is the beach, the splash parks, the sprinklers, the swimming pools...and science experiments.

This experiment, constructed of very simple supplies, demonstrates how a hydroelectric power station works. Many dams produce hydroelectric power by harnessing the incredible power of falling water to turn enormous wheels (called turbines) that then drive machines (called generators) that produce electricity. The Hoover Dam is one of the largest dams of this kind, providing electricity to Arizona, Nevada, and California.

This idea came from 50 Science Things to Make & Do, one of our very favorite science activity books. Ready to see how water power works? Let's get started.

Total Time: 30 minutes to make your bottle, then only a minute to do the experiment
Safety Concerns: An adult will need to do the cuts in the bottle. Because the plastic is slippery, cutting it can be dangerous for anyone!

Materials You Need:
A two-liter bottle
Scissors
Thumbtack
Pencil
2 straws, cut into 1-inch long pieces
Tape
String
A pitcher full of water

Directions:
  • Cut the top off the bottle. If there are sharp edges be sure to put some tape over them so nobody gets hurt!
  • Using the thumbtack, poke six holes around the base of the bottle. Use the pencil to widen the holes. Don't be dainty here, it takes some real muscle to make those holes!
  • Push a straw piece into each hole and secure it with tape.
  • Make three holes at the top of the bottle and tie a piece of string through each hole. Each string should be about the same length.
  • Tie all the strings to a fourth piece of string at the top.
  • Making sure you are outside or in a bathtub, pour water into the bottle and watch it spin as the water pours out of the straws!
Print These Instructions

Check out our video when we did this experiment. I apologize in advance for the background noise: we live on a very busy street! When we do this experiment again we are going to put the holes for the straws lower. We found that the more water in the bottle, the faster it spun around, so putting the straw holes further down should make it spin faster. It would also be fun to experiment with bottles that are taller/shorter and see if it makes a difference if you put more or less straw holes in the bottom. We have a lot of hypotheses to test!
Want more plastic-bottle-inspired fun? Check out the amazing upcycling some people are doing with their two-liter bottles and caps.
Also makes a great bath toy!
TGIF Linky Party hosted by 123Homeschool4Me
Head on over to 123Homeschool4Me to get tons of free kid activities for the weekend!

Saturday, July 26, 2014

Eggsperiment

Have you ever wondered what the cells inside of your body look like? Doing some experiments with chicken eggs can give you a pretty good idea. This is a great experiment to do in conjunction with a human biology unit or for a science project at school!

We will be using vinegar to eat away the shell of an egg and then observing what is hidden inside. We'll also learn a good deal about osmosis. Ready? Let's go.

Total Time: Several days to completion
Safety Concerns: Always make sure to wash your hands after handling raw eggs. Be careful not to get any vinegar in your eyes either!

Materials You Need:

Part I
2 eggs
2 cups of vinegar (white or cider)

Part II
Food Coloring
1 cup of corn syrup
1 cup of water

Directions, Part I:
  • Put each egg in a cup of vinegar. The egg will float at the top and a bit will hover above the surface, which is just fine.
  • Place your cups in the refrigerator for a couple of days, checking every 12 hours or so to see when the shell is completely gone. What do you see?
You should observe bubbles on the surface of the egg almost immediately. Those bubbles are carbon dioxide gas forming due to the reaction between vinegar (which is acidic) and the calcium carbonate egg shells. Over time the vinegar will completely dissolve the entire egg shell.

What does it feel like? What does it look like?
Now for some fun with your shell-less eggs! Carl Nelson, over at Imagination Station Toledo, wrote a whole article about different experiments to try with what he calls "naked eggs". One experiment that we did brilliantly illustrates the principle of osmosis.

The membrane of a cell (in this case, the egg) is semipermeable, meaning that small particles can go in and out of the cell while large particles stay out. Water and other nutrients are small enough to travel in and out of the cell. When the concentration of water in the cell is different than the concentration of water outside of the cell, the water will move either in or out of the cell in order to balance the concentration inside and out. This is called osmosis.

The next part of our experiment will show you how to make your naked egg get big and plump and also how to make your egg shrivel, depending on what liquid you immerse your egg in next. Get ready to watch osmosis happen!

Directions, Part II:
  • Fill one cup with water. Add a few drops of food coloring. (We did red.) Put one shell-less egg in your cup.
  • Fill another cup with corn syrup. Add a few drops of food coloring and stir it around. (We did green.) Put the other shell-less egg in that cup.
  • Put both cups back in the refrigerator and wait for a day or two. Then pull them each out and note what you see.
The egg that was in the the water should be big and beautiful. This is because it has absorbed water from the cup. You can even see how the food coloring has made it through the membrane to color your egg! An egg is about 90% water so when it is immersed in 100% water, some of that water will go inside of the egg to try to equalize the concentration.

The egg in the corn syrup is a different matter. Corn syrup has a very low concentration of water in it so some of the water from the inside of the egg will travel through the membrane to the corn syrup. This makes the egg shrivel up and get smaller.

You can see from our experiment that the egg turned green from the corn syrup. This shows that water is constantly moving across the membrane, in and out of the egg. Overall, though, the egg loses water through osmosis because the concentration of water is lower on the outside than it is on the inside of the egg.

Next time I want to try putting the shriveled egg into a cup of water to see if it will swell up again. What do you think will happen?

Print These Instructions
This post is in conjunction with the monthly Homeschool Science Share and Tell Link-Up. Head on over to see tons of great science ideas from several different bloggers and to link up your own blog!

Wednesday, May 28, 2014

Simple (and Scientific) Homemade Ice Cream

Our family doesn't currently own a car so all of our travel is done via our own two feet, biking, and the occasional bus ride. On really hot days this causes us to ravenously burst through the door in search of cold stuff to shove into our mouths.
I came across this fantastic recipe for homemade ice cream last year. We have enjoyed it several times both as a family and in our Science Kiddo classes. The thing I like the most about about this ice cream is that you don't need any special equipment or ingredients to make it. Plus, it is a delicious and refreshing way to learn some science!

To make any variety of homemade ice cream you need to partially freeze your milk or cream. Water freezes at 32°F, but because milk contains proteins and fat it freezes at a lower temperature. This means that trying to freeze milk with ice cubes won't work. You need to add a special ingredient to your ice cubes to make a mixture that is colder even than ice alone. Ready for the secret ingredient? I'll give you a few clues. It's white. It's something almost everyone has in their kitchen. It tastes yummy on popcorn with butter. It's....SALT!

We talked about the magical science of how salt and ice cubes work when we did our Fishing for Ice experiment and when we made our delicious fruity slush. When you add salt to ice, it lowers the freezing point of the ice, making it melt. You are left with a salty-icy-watery mixture that is much colder than 32°F. The temperature of your salty mixture is close to 0°F! (You can verify this with a thermometer.) This temperature is cold enough to freeze milk, thus enabling you to enjoy yummy homemade ice cream in less than 10 minutes. Put it atop your morning waffle if you so desire.
Total Time: 10 minutes or less
Difficulty: The one trick with this experiment is making sure you don't contaminate your ice cream mixture with your salty water. This leads to yuckiness.

Materials You Need:
One small Ziploc baggie (quart or sandwich size)
1/2 C. milk (whole works best, but any variety will be fine)
1 Tbsp. sugar
1/4 tsp. vanilla
One gallon-size Ziploc bag
8-10 C. Ice
6 Tbsp. salt

Directions:
  • Add milk, sugar, and vanilla to the small baggie. Seal the bag, being careful to release excess air.
  • Add ice and salt to the bigger baggie.
  • Place the small baggie into the large bag of ice and salt. Seal the large bag.
  • Shake for about 5 minutes or until the milk mixture turns into a soft solid.
  • This is the tricky part: Open up the large bag, remove the small bag and rinse it off quickly in cold water (pay special attention to rinsing off the opening). You don't want any of the salt water getting into your sweet and creamy ice cream!
  • Either grab a spoon and eat your ice cream right out of the bag, or pour your ice cream into a bowl. Either way, eat it and enjoy!
Print These Instructions

Sunday, May 25, 2014

Fruity Ice Slush

Did you know you can make your own delicious slush drink without a freezer? This is the ideal experiment to do on a hot summer day when all you want to eat is something freezing cold and delicious. With lots of those days up ahead, we hope you really enjoy this tasty slushy science!
I pulled this idea from one of our favorite experiment books, 50 Science Things to Make & Do. I love this book because it contains tons of simple science ideas with easy-to-follow instructions. Even my four-year-old can do many of the experiments on his own :)

Total Time: About two hours.
Difficulty: With just a few ingredients and some simple stirring, this is one of our safest and easiest experiments yet!

Materials You Need:
Mixing Bowl
Ice
3 Tbsp. Salt
Fruit Juice (any variety should work just fine)
Spoon

Directions:
  • Fill your mixing bowl with ice.
  • Add the salt and stir it in.
  • Place a glass upright in the middle of the ice and fill it halfway with juice.
  • Stir the juice every 10 minutes for about an hour and a half.
  • Stir it every 5 minutes for another half hour until it turns slushy.
  • Eat and enjoy!
Print These Instructions

Our Fishing for Ice experiment and Easy Homemade Ice Cream involve the same science that makes the fruit drink in this experiment turn from liquid to solid without the aid of a freezer. When you add salt to ice it lowers the freezing point, making the salty icy mixture colder than ice alone. If you have a thermometer you can verify this fact. Ice freezes at 32°F, but when you add salt the ice melts and the mixture gets down to around 0°F. This is cold enough to freeze juice! Stirring the juice frequently ensures that the frozen parts mix with the liquidy parts, making a yummy slushy mix. If you leave your juice long enough it will freeze solid! Maybe next time we will try making our own popsicles this way...

Thursday, May 15, 2014

Ant Attack!

Sometimes science experiments are complicated and require a lot of materials and detailed instructions. However, science experiments can also be incredibly simple while being just as fun and interesting as the complicated projects.

This experiment is very simple and basically takes no time at all. All you need to do is cut up an apple and place one slice near some ants (probably best to place the apple several feet away from your house so the ants don't come inside!). It's preferable if the apple is on some concrete so you can see the trails that the ants follow.

Watch what the ants do. Do they carry pieces of the apple away? Where do they carry the pieces? Do the ants follow the same path every time? Do they help each other or do they fight?

Check your apple slice after one hour. Are there more ants? What are they doing?

What happens if you move the apple an inch or two to the side? What do the ants do?

Watching how ants work together can be fascinating. Ants leave trails of chemicals called pheromones that alert other members of the colony that there is food on the path. This is why each member of the colony continuously walks the same route to the food and back to their nest. What happens if you place a leaf or a rock in the middle of their path?

This experiment will turn a lazy summer afternoon into an exciting discovery of ants and their behavior. Enjoy!

Thanks to 50 Science Things to Make & Do for this fantastic idea!

Thursday, April 17, 2014

How to Dye Eggs Naturally Using Acid/Base Chemistry

One of the things I anticipate most about this season is dying eggs with my family. It's one of those things that is always fun no matter how old you get. This year we added another fun dimension to our egg-dying party by incorporating acid/base chemistry into it. For those of you who love science AND love doing things naturally (even organically!), this is the perfect activity for you.
The star of this show is red cabbage. It contains a chemical called anthocyanin that changes color depending on the acidity of its environment. This means it is a pH-indicator, a gauge that tells you how acidic or basic the surrounding environment is. Red cabbage is purple in a pH-neutral environment, but it turns pink in an acidic environment and bluish-green in a basic environment. We recently did another experiment with red cabbage where we froze cabbage-water into ice cubes and tested the acidity of different solutions. It's the same chemistry, just a different way to see it.

Total Time: This experiment takes awhile, though you don't have to actively be doing anything for most of the time. Allow about 40 minutes to boil the eggs and cabbage and at least 12-18 hours for the eggs to sit in the fridge in the cabbage solution. Painting the eggs only takes 10-20 minutes at the end.
Safety Concerns: As always, be careful when boiling things with kids around. Use caution when cooking and handling the hot eggs and cabbage.

Materials You Need:
One half of a head of red cabbage
One dozen large eggs
Slotted spoon
Lemon juice or vinegar
Baking soda
Q-tips or paint brushes to paint the eggs

Directions:
To prepare the eggs:
  1. Place eggs in a large pot in a single layer.
  2. Chop up your cabbage into small pieces and throw them into the pot with the eggs. Add enough cold water to cover everything by one inch.
  3. Bring the cabbage/eggs/water mixture to a boil. Remove from burner and cover the pot.
  4. Let your mixture stand for about 12 minutes for large eggs (9 minutes for medium eggs, 15 minutes for extra large eggs).
  5. Using a slotted spoon, remove your eggs from the pot and cool completely under cold running water or in a bowl of ice water. They will most likely still be very white at this point.
  6. Refrigerate your eggs. Once your cabbage water has cooled to room temperature, place your eggs back into the pot and refrigerate everything together. Make sure the eggs are completely submerged in the water for best color.
  7. Leave your mixture in the refrigerator overnight.
 To paint your eggs:
  1. Use a spoon to scoop your eggs out of the cabbage mixture. Feel free to rinse them off and pat them dry. They should be some shade of bluish-purple (depending on how acidic your tap water is!).
  2. Pour some lemon juice or vinegar into a small cup (this is your acid).
  3. In another cup mix 1/2 tsp baking soda with enough water to dissolve it (this is your base).
  4. Using your Q-tips or paint brushes, paint your eggs! Watch as your eggs change from blue to pink when you paint with lemon juice and from blue to greenish-blue when you paint with your baking soda solution (this may not show up well until the eggs are dry again).
  5. Feel free to try painting your eggs with other solutions from around the house to see what happens. Some ideas to try are washing soda, cream of tartar, and antacids. If your egg turns pink you know the solution is acidic, if it turns green you know it's basic!
Something interesting that I noted was that the cabbage solution turned out very blue this time, whereas last time we did this experiment it was beet red. We moved to a different county since last time, so does that mean our drinking water is more basic on this end of the city? Or is it a difference in the cabbage I purchased each time? I don't know, but I think it's definitely worth finding out!

Print These Instructions
You can see the whitish-pink spots where we painted with lemon juice. On the right of the egg you can see it's a little bit green, which is where we painted with baking soda.
Thanks to the Kitchen Pantry Scientist for this awesome idea!

Wednesday, April 16, 2014

DIY Window Gel Clings

Window gel stickers? Window jellies? Window gels? I really don't know what they are called, but my kids love them. How would you like to make your own gel clings that are not only cute, but also edible? I thought so.

Now before you think I have gone too artsy on the Science Kiddo, just stay tuned. There is a ton of science your kids can learn from this in addition to it being a great creative outlet and fun activity for you to do as a family.

It's really simple and only takes a few ingredients. Our window jellies turned out beautiful and fun, just in time to catch the sun's warm spring rays in our window.

Total Time: About 20-30 minutes
Safety Concerns: You will need to boil water for this. Just watch your kids around hot water and the resulting hot gelatin. Let it cool a bit before your kids get close.

Materials You Need:

Four cups of boiling water
Six packets of unflavored gelatin
Food coloring and glitter of your choice
A toothpick
One large cookie sheet with a rim or two 9 x 13 casserole dishes
Cookie cutters
Spatula


Directions:

  • Add the gelatin to the hot water. Stir to make sure it all dissolves and spoon out any bubbles.
  • Pour your mixture into whatever containers you want. You want it to be about half an inch thick. It doesn't have to be exact, but it is best if it is level. Bowls won't work very well since the gelatin won't be a uniform depth.
  • Once gelatin is cooled a bit, but before it hardens (you have about a 45-minute window here) have fun dropping food coloring into your gel and swirling it around with your toothpick. Sprinkle it with glitter if you desire.
  • Let the gelatin harden. It should only take 30-60 minutes. Since it's super-concentrated it hardens quickly without being in the refrigerator.
  • Once it has set use cookie cutters to cut out shapes or cut out your own shapes using a butter knife.
  • Use a spatula to lift your gel shapes out of the pan. Don't worry if they tear because you can simply mold them back together. Stick them to your windows and enjoy!
Print These Instructions

Easy, right? One thing I love about decorating the gelatin is that it is much more viscous, or thicker, than water. This means that you can decorate each corner differently and the colors/glitter won't run into each other. You can customize the colors and shapes for whatever holiday or season you want!

If you want to incorporate more science into this activity you could pour some water into a pan, drop colors into it, and compare how it behaves differently from the gelatin mixture. Then do the same thing with vegetable oil. (We did this in our Color Bombs experiment.) You could also observe how your window gels evaporate after a few days on the window, leaving behind paper-thin dry shapes.
Note: You probably won't be able to take these jellies off your window and put them back on more than a few times before they tear beyond repair. They are slightly more delicate than the window gels you buy at the dollar store.

Thanks for the great idea, Kitchen Pantry Scientist!

Wednesday, April 9, 2014

Which One Will Freeze the Fastest?

This article was contributed by Jen, a homeschooling mom of three from Beaverton, Oregon. In February the Portland area was hit by a huge snowstorm for these parts and the entire city basically shut down. Jen did this awesome experiment with her kids while they were hunkered down at home.

We took advantage of the snow storm and subfreezing temperature in February to have a little Science Snow Fun! What we did was fill balloons (and a few random party bags) up with water, added some food coloring, and laid them out in different locations outside. 

You’ll see the bags and a balloon on our back deck:
And a few balloons set up on/around a table in the backyard. Will had a clever idea to suspend one balloon from the table itself - see the light blue balloon in the picture below :)
Enter the hypothesis!! We guessed that the balloon suspended in the cold air would freeze the best, as the balloons surrounded by snow (not unlike a snow cave) would stay closer to the 32 degree mark. We weren’t sure how much the wood from the deck would affect the balloons.

In all fairness, to have a truly scientific experiment, we should have filled the balloons all the same size, but without a hose, we were just lucky to get the water in the balloon in the first place :) 

We waited overnight - and then examined each of our balloons/bags.

The bags up on the deck formed crystals, but were mostly liquid:
This was the balloon that had its own snow cave…. Logan is going to open it up… and you’ll see the lesson we learned the hard way: don’t dye balloons with red food coloring…
Not a good choice of color… sorry :(

Moving on!! Here’s Logan taking down the balloon from the table - check out how much snow is actually ON the table!!! 
The balloon that was suspended from the air was the ice “balloon” on the right. The one on the left was a balloon that was on the table, BUT did not have a snow cave around it to keep it “warm” and so it too because an ice balloon :) 
Conclusion: The balloon on the metal table and the one hanging from it froze the best. The balloon and bags that were sitting on the wooden deck hardly froze at all. We think this is because the balloons on the table received cold circulating air from all sides. Plus, metal is a better conductor than wood, meaning that the balloon on the metal table got colder than the balloon that was sitting on the wooden deck.
 
So much fun!!

I love that Jen and her kids used their time at home to have some fun, ask some scientific questions, and discover some new things together. What are some scientific things your family has learned this winter?