STEM Activity: Ice Excavation
Get ready to go on an arctic adventure! Learn about ice excavation in this exciting ice science experiment while discovering why water freezes and ice melts.
- Clear cup
- Food coloring
- Ice cube tray
- Fruit or plastic toy figures, small
- Spoon or craft sticks
Raid your refrigerator and gather several small pieces of fruit or other small objects that can get wet. With an adult’s help, place the items inside an ice cube tray, fill with water and place in the freezer to create frozen artifacts. For an even bigger challenge, grab a balloon and insert a few of the plastic figures, fill it with water until it is about the size of a water balloon and place in the freezer. Once everything is frozen, place the ice cubes in a cup of water. Take your string and try to fish the ice cubes with frozen artifacts out of the water. Any luck? Nope! Those ice cubes are too big and slippery to catch with one piece of string.
Now, sprinkle the ice cubes with salt and wait a minute or two. Go fishing for frozen artifacts again with your string. Catch anything? Yes? Cool — check out the science behind it below to find out why!
Now, place the ice cubes on a tray and if you have it, peel off the balloon and place the ice ball on the tray. If an adult says it is okay, place a few drops of food coloring on each piece of ice. You might think the ice is 100% solid, but now you can see how the color finds its way into all of the small cracks in the ice.
Now for the excavation! Use spoons or craft sticks to chip and dig your way through the ice, uncovering the frozen artifacts. To speed up the process, sprinkle salt on top of the ice and observe what happens.
Educators: Use this activity in the classroom with these modifications!
To prepare this activity for an entire class, use ice cube trays with small toys such as game pieces or Legos. Prepare one to two ice cubes per children and have a handful of salt shakers the students can share.
What are we learning?
What is ice? Yes, ice is frozen water, but did you know that the hydrogen and oxygen atoms found in liquid water lock together in patterns when the water is cooled below 32°F, forming a crystal? The crystals take up a lot more space than the moving liquid molecules in water, which is why if you freeze a full bottle of water, it bulges out. It’s also why ice cubes float! Another cool fact — ice has 15 different crystal forms!
Why does salt make ice melt? This reaction happens because salt lowers the freezing point of the ice, meaning that the temperature has to be even lower for the water to stay frozen. Why did the string catch the ice cubes after using salt? The salt melted the ice, but since it was only a small amount of salt, the water around the ice cubes rapidly froze again, trapping the string in the newly formed ice layer!
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