by Mabel Sterritt
When doing science experiments with your kids, it’s fun to write down what’s happening as you go. To be an authentic scientist, you should follow the scientific method; these are the steps that real scientists follow when they’re going through an experiment. First, you must figure out the purpose – why are you doing this experiment and what are you trying to figure out? Next, research your experiment. What do you need to know to answer your question? The next step is to form a hypothesis, or prediction about how your experiment will turn out. Once all of this is done, you can actually perform the experiment! Analyze the results and come to a conclusion for these five science experiments. Try each of these science experiments with your kids this summer to help beat the boredom!
Purpose: Is ooblek a solid or a liquid? Is it both?
Research: Ooblek is a strange material that is similar to silly putty. When you touch the surface, it feels hard like a solid material. But if you slowly plunge your hand into it, you’ll notice that it begins to take on the properties of a liquid.
Hypothesis: If we apply different amounts of pressure to the ooblek, then it will change forms from a solid to a liquid.
- 1 cup of water
- 1 to 2 cups of cornstarch
- Mixing bowl
- Food coloring (optional)
- Pour one cup of cornstarch into the mixing bowl.
- Pour the water into the mixing bowl, slowly mixing it with the cornstarch until the mixture becomes thick. It should harden when you tap it. Too runny? Add more cornstarch. Too thin? Add more water.
- Add food coloring if desired.
- Drop your hands quickly into the mixture, and then drop them slowly into the mixture. What happens?
- Hold a handful in your open palm. What happens?
- Roll the ooblek out or squeeze it in your hands. Does it change?
Conclusion: You’ll notice that the quicker you move with the ooblek, the harder it feels. This is because when you tap it quickly, you’re forcing the cornstarch particles together; when you move your hand through it slowly, the cornstarch particles have more time to move away from your hand. This simple change in pressure is the reason why ooblek is similar to quicksand. How would you escape a vat of ooblek?
FLOATING PING-PONG BALLS
Purpose: Why do ping-pong balls float in the air when you put hair dryers under them?
Research: Ping-pong balls may be lightweight, but they certainly don’t have wings. Does their weight play a role in why they can be suspended over the air of a hair dryer? Or is it because of the role that gravity and air pressure plays?
Hypothesis: If we make the ping-pong ball float, then it will stay in the air vertically.
- 2 to 3 ping-pong balls
- A hair dryer
- Plug in the hair dryer.
- Put the hair dryer on its highest setting and point it straight up.
- Place your ping-pong ball above the hair dryer.
- What happens when you put your ping-pong ball over the air?
- What happens when you point the hair dryer horizontally instead of vertically?
- What happens when you put the hair dryer on a lower setting?
Conclusion: Because of air pressure, the ping-pong is able to stay afloat. When the hair dryer is on, it creates a low air pressure chamber. The air pressure around the hair dryer is higher, and because of this, the ping-pong ball is forced to stay in the lower pressure column of air. Can you float two or even three ping-pong balls under the same hair dryer?
For more experiments, go to the next page!
by Mabel Sterritt
DIET COCA COLA AND MENTOS
Purpose: What creates the small explosion that happen when you put Mentos candy into a bottle of diet coca cola?
Research: One of the most popular experiments of the modern day, the diet coca cola and Mentos experiment has been tried by many and left many indoor spaces in disarray. But why is it so messy? When soda is manufactured, carbon dioxide is added to the bottles; this makes the fizz and fuzz that appears on the top of your drink. Up until you open the bottle, a lot of carbon dioxide gas is waiting to be released. When you speed up the process, you get explosive results.
Hypothesis: If we add Mentos to the diet coca cola, then the coca cola will fizz up and explode.
- Large bottle of diet coca cola
- Pack of Mentos
- Stand the diet coca cola upright and unscrew the lid. Make sure you’re outside for this experiment.
- Drop the Mentos into the coca cola and run! It won’t be long before a small geyser erupts, covering the area in a sticky layer of diet coca cola.
- What happens when you open the bottle? Does it fizz or do you hear sizzling sounds?
- How many Mentos did you drop in the bottle?
- How high was your geyser?
Conclusion: By stimulating the carbon dioxide with the Mentos, you allow a huge amount of bubbles to form, which in turn causes an explosion. Mentos candies are covered in small dimples similar to a golf ball, and because of this a tremendous amount of carbon dioxide bubbles form on the surface. When the bottle can’t contain the bubbles, the explosion occurs!
MAKE A RAINBOW
Purpose: What makes rainbows?
Research: Some people think leprechauns create rainbows and if you follow one to the end you’ll find a pot of gold. But there is a scientific reason behind the seven colors in the sky and it all has to do with refracting (bending) sunlight.
Hypothesis: If we hold a glass of water in direct sunlight, then the light will bend and create a rainbow.
- A glass of water, about three quarters full
- White paper
- A sunny, well-lit room or a sunny spot in your backyard.
- Take the glass of water and paper to your desired sunny location.
- Hold the glass of water above the paper and watch as a rainbow appears on your paper!
- What happens when you put the glass of water underneath the paper?
- What happens when you change the angle you hold the glass? The height?
- What happens when you use less sunlight? Less water?
Conclusion: Rainbows are formed when sunlight refracts (bends) as it passes through raindrops. This is why you often see rainbows in the sunshine after storms. It acts the same way in your glass of water. The sunlight is able to bend and form the seven colors of the rainbow.
For more experiments, go to the next page!
by Mabel Sterritt
Make a Lava Lamp
Purpose: What makes the substances in the lava lamp not mix?
Research: Have you ever had to shake salad dressing before putting it over your salad? Oil and water don’t mix well together, and that is the basis of this experiment. When you mix two substances with different densities, you can create your own funky lava lamp with a few simple ingredients.
Hypothesis: If we mix the oil and water, then the substances will separate because of their differences in density.
- A clear plastic bottle
- Vegetable oil
- Food coloring
- Pour water into the bottle until it is about a quarter of the way full.
- Pour in the vegetable oil until the bottle is about halfway full.
- Wait until the water and oil separate.
- Add about a dozen drops of your favorite color of food coloring to the mixture. Watch as the food coloring drops down to the bottom of the bottle.
- Cut an Alka-Seltzer into about 5 or 6 smaller pieces and drop them into the mixture. Things will start getting fizzy and you’ll have your own lava lamp!
- What happens when you add vegetable oil to the water?
- Does the food coloring mix with the oil or the water?
- What happens when you add the Alka-Seltzer tablets?
Conclusion: Because of their differences in density, the oil and water don’t mix and will therefore separate when you add them to your lava lamp. By adding the Alka-Seltzer, you’re releasing small bubbles of carbon dioxide that will fizz to the top and bring the colored blobs along with it.
Did you try one of these experiments? Share your comments below! We'd love to hear from you!
Mabel Sterritt is an intern with Boston Parents Paper.