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A Frost Wedging Experiment for a Kid

Frost wedging is a phenomenon that usually occurs over time in extremely cold climates. When water seeps into the cracks of stone (called joints), it undergoes a freeze-thaw cycle. As water freezes it expands, putting pressure on the joint until it gives, deepening the crack until the stone eventually splits.Though frost wedging can take as long as a year to happen, there is a simple experiment you can use to demonstrate to your child the expanding properties of water.

Materials
- Collect the following items:
  
  16 or 20 oz. plastic water bottle
  
  Colored markers
  
  Tap water
  
  Make sure the water bottle is clean and that the markers are nontoxic and kid-safe. If you must use paint markers or anything similar, be sure to do so outside or in a well ventilated area. As always, make sure that children are properly supervised with these markers. If the children are too young to use paint markers, be sure to keep them well out of reach.
Setting Up the Experiment
- Open the plastic bottles and fill them halfway with tap water. You can either let the child do this, or do it for them. Be sure to supervise small children around water at all times to avoid accidental injury. Close the bottles and allow the child to decorate the bottle as they like. When finished, place the bottle on a level surface so that the water can even out. Use a black marker to mark the level of the water. Let the ink dry before you continue.
Performing the Experiment
- Clear a space in your freezer to accommodate the bottle. Be sure that everything in the freezer is stable to prevent the bottle from falling and ruining the experiment. Once the space is secure, remove the lid from the bottle and place it in the freezer. Allow the water to freeze completely. This process should only take a few hours at most. You can allow the child to look in to watch the water's progress as it freezes and rises. When the water is completely frozen, it will have expanded well above the marked line.
The Explanation
- Use this as an opportunity to explain the principles of expansion and contraction to your child. Most materials expand when heated and contract when cooled; water is the same, up to a certain point. After reaching freezing temperatures water actually begins to expand due to unique properties of its molecules, which cause it to align in a precisely spaced lattice structure similar to crystals, causing the molecules to take up more space. You can explain this to your child by compariing molecules to the building blocks in toy sets like Connex. Water is made up of molecules just like towers in Connex are made up of smaller parts. When disassembled, the parts take up little space and can be stored close enough together to fit into a box. When you arrange them in a precise configuration, though, the shapes they take to form a stable structure cause them to take up more space until one box of Connex can nearly fill a room.

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