With the kids home from school for a few days this Thanksgiving break, why not take the time to do some hands-on learning? Consider making a craft that gives you and your child an opportunity to spend some time exploring science and creating together, an experience you’re both sure to be thankful for. Get ready for some parent-child quality time with this DIY experiment from Jonathan Adolph’s “Mason Jar Science!”
Grow some underground décor for your kid cave.
You think growing bigger takes a long time? Try being a stalactite. Those drippy columns you see in caves grow just a few inches every thousand years! You can observe how they do it by growing your very own string of stalactite crystals. The best part is, it won’t take a thousand years! (More like a week.) Set up your experiment where no one will touch it, check your drip bowl every day, and watch what happens.
Materials
- 2 pint-size mason jars
- Piece of yarn, about 4 feet long
- Scissors
- 2 bendy straws
- Skewer or pipe cleaner
- Hot tap water
- Baking soda, about 1/2 cup
- Spoon or other stirrer
- Food coloring (optional)
- Bowl for drips
Instructions
- Fold the yarn in half and twist it together to make a thick strand. Cut the bendable “elbows” from the straws, leaving about an inch of the straight part on each end. Thread the straws on the yarn, using a skewer or pipe cleaner to push the yarn through.
- Fill the jars about two-thirds full with hot tap water. Spoon in baking soda, a tablespoon at a time, to each jar and stir to dissolve it. Keep adding baking soda and stirring until the powder no longer dissolves and instead starts to gather on the bottom of the jar (it should take 3 to 5 tablespoons for each jar). You’ve created a saturated solution (see Fun with Crystals, page 30). Add a few drops of food coloring if you want.
- Set up the jars up as shown, with the drip bowl between them. Remember: the crystals are very delicate and will fall easily if jostled, so set up your experiment in a place where you can leave it for several days.
- Soak the yarn in the solution, making sure it’s wet all the way through the straws. Hang it between the jars using the elbows to hold it in place as shown. The ends of the yarn must be in the solution and the center of the yarn must be lower than the level of the solution in the jars, forming a drip point.
What to Watch For
The solution should start dripping into the bowl right away. You’ll begin to see crystals form after a day or so. Over the next few days, observe how much they grow. When the bowl gets full, carefully pour the solution back into the jars.
What’s Going On
Baking soda, or sodium bicarbonate, is a crystal, meaning it forms in a distinctive shape. As the solution of dissolved baking soda moves through the yarn, thanks to capillary action, the water evaporates, forcing the baking soda to form again as a solid, a process called crystallization.
Speak Like a Scientist
Here’s a handy way to tell your stalactites from your stalagmites: stalaCtites hang down from the C-ling while stalaGmites rise up from the G-round.
Science in Real Life
Real stalactites are created through a similar process. In certain caves, water flows through soft rock, such as limestone, and carries away dissolved minerals. As the mineralized water drips from the ceiling it creates an icicle-like column of minerals and crystals. The world’s largest stalactite is more than 25 feet long!
Excerpted from Mason Jar Science © by Jonathan Adolph. Used with permission from Storey Publishing. Photo by © Mars Vilaubi
