Last week my son woke up from his afternoon nap and said, “I want to do a science experiment, Mama.” This request was completely out of the blue, and I was so proud. I’ve been trying to do anywhere from 1 to 4 science experiments per month with my son for the past 6 months. It’s so rewarding for me to see that he is enjoying the experiments and wanting to learn more.
When he asked for the experiments I didn’t have any planned, but there was no way I was going to tell my my son “no, I don’t have any experiments, sorry.” So I had to think fast.
My son has been into marine animals lately – ever since he received a bucket full of marine animals for Christmas. He loves playing with his marine and artic animals and learning about them. He often talks about where they live and how they survive in the cold. I decided to use these animals as inspiration for a few ocean themed experiments.
I remembered a fun experiment they demonstrated at our library to teach kids how the arctic marine animals survive in the cold because of their layer of blubber under their skin. I also remembered finding some pins on Pinterest awhile back about grapes floating in salt water.
These two experiments are simple, quick and use materials I already had on hand at the house. I was able to plan and set up these ocean themed experiments in minutes after my son’s request.
Let’s talk about blubber
Arctic animals can live in extreme conditions. Many of the warm-blooded marine animals who live in the arctic survive in theses cold temps thanks to blubber acting as an insulator. Blubber is a thick layer of fat beneath the skin. It covers the marine animal’s whole body except for fins and flippers.
The blubber insulates the animals from the cold water temperatures in the arctic waters, it increases their buoyancy, and it stores energy (made of proteins and fat) to prove nutrients in times where food is scarce.The blood vessels in the blubber constrict, reducing the flow of blood and reducing the energy required to heat the body, which conserves heat.
In this experiment we use shortening to demonstrate the insulating effects of blubber. Shortening is fat that is solid at room temperature. It can be made of lard or vegetable oils.
Let’s talk about why things float in salt water
Ocean water has an average salinity of 3.5%. This means that there are 35 grams of dissolved salt per liter of of ocean water. Of course there is a lot more in ocean water composition than just water and salt due to the natural chemistry of the ocean water, the plants and animals that live in it, and also from human contamination.
However, for simplicity in today’s experiment and to explain the basic concept to preschoolers and toddlers, we’re saying ocean water is salt water.
The density of an object is mass times volume. Adding salt to water increases the water’s mass without adding much volume, so this increases the water’s density.
Objects float due to buoyancy. Buoyancy is the upward force on an object from a fluid. It is determined by the density of the object being dropped into the fluid and the density of the fluid being displaced. If you’re dropping the same object into salt and fresh water, it will have greater buoyancy (float better) in the salt water because the salt water has greater density.
In the blubber experiment, there is an option to enclose the shortening in ziplock bags. If you choose to do this, please monitor your children while they play with the ziplock bags to be sure the bags never go near their faces. It’s always a good idea to have a talk with your children before starting to instruct them to keep plastic bags (and all materials used in the experiment, really) away from their faces.
Shortening is a food product, so it is a pretty safe material for your kids to play with, but just keep an eye on your kids, especially young toddlers, so that they don’t rub their eyes with shortening on their fingers or try to eat too much of it.
Finally, for both experiments be sure to protect the surfaces that you will be working on because you may end up with (salty and sugary) water spilled on your surface.
Both experiments are appropriate for kids age 1+. As the kids get older they can participate more independently. My 3.5 year old son could do all steps of both experiments by himself, while my 16 month old daughter could participate in both experiments with supervision and assistance from me.
Arctic Animals Blubber experiment: Can you feel the cold?
In this experiment your children will learn about how blubber protects arctic animals from the freezing cold temperatures.
- Large glass bowl
- Ice cubes
- Ziplock bags
- Packing or duct tape
- Arctic or marine animals (optional)
Keep the kids clean method (both my kids were very hesitant to stick their hands in the bags as explained in this experiment):
- Fill a sandwich size plastic bag about half way full with shortening
- Place a second bag inside the first bag
- Duct tape the top of the two bags closed (now you have shortening secured between two bags so there will be no mess!)
- Push the shortening around so it covers all sides of the bag
- Fill a large glass bowl with ice water
- Place your child’s hand inside the bag filled with shortening and see how long they can keep their hand inside the ice water (they should not be able to feel the ice water at all through the layer of shortening protecting their hand)
- Have your child place their bare hand into the ice water and see how long they can keep it there
Your child will discover that the “blubber” protected their hand from the cold!
Alternate messier method (of course my kids preferred this one…):
- Fill a large bowl with ice water
- Cover your child’s index finger with a thick layer of shortening
- Have your child place their finger covered in shortening into the ice water and see how long they can keep it there
- Have your child place their bare finger into the ice water and see how long they can keep it in there.Your child will discover that the “blubber” protected their finger from the cold!
When your child first touches the ice water with bare hands it will feel very cold to them. Then when their hands are protected from the cold with the shortening, they do not feel the cold. The shortening simulates the protection blubber provides to arctic marine animals. The blubber acts as an insulator keep in the body heat and protect the arctic animal’s internal organs so they can survive in freezing conditions.
Water density experiment: Does it float?
In this experiment your children will learn about how salt and sugar affect water density.
- 3 glasses
- 6 cups water
- 1/2 cup salt
- 1/2 cup sugar
- Cherry tomatoes, grapes, or eggs (I used tomatoes because that’s what I had on hand)
- Fill each of the 3 glasses with 2 cups of tap water
- Add 1/2 cup salt into one of the glasses and stir until it completely dissolves
- Add 1/2 cup sugar into another of the glasses and stir until it completely dissolves
- Line up the 3 glasses of water (one tap water, one salt water, one sugar water) in front of your child on a table
- Have your child drop the tomatoes into the glasses one at a time and see if the tomato sinks or floats
The cherry tomatoes float in salt and sugar water because the salt and sugar add mass to the water making it more dense. Objects float better on a denser fluid because the force of buoyancy is greater, so the tomatoes floated best in the salt water, better in sugar water, and did not float at all in tap water.
Why did the tomatoes float better in salt than sugar water? Although 1/2 cup sugar actually weighs more than 1/2 cup salt, sugar is not as soluble as salt in water. Thus not as much sugar will dissolve into the water, so sugar water will be less dense than salt water (more salt dissolved into the water increasing the mass of the water). This means sugar water will have less buoyancy than the salt water.
I hope you and your kids enjoy learning about the ocean and the arctic animals that live in it with these simple and fun experiments. Let me know if you try them out and if your kids like them!