Step 1

Boil the water. To make baking soda crystals, you start by making a water solution that’s saturated with baking soda. The baking soda will dissolve better in warm water. Measure 2 cups (470 ml) of water into a kettle. Turn on the kettle to boil the water.Be very careful when using appliances and electronics. Ask a parent, guardian, or adult to help you.

Step 2

Pour the water. When the kettle boils, carefully pour the water into a large heat-proof bowl, glass, or jar. Be very careful not to spill the water, as it’s very hot and can burn your skin. You may want to ask an adult to pour the water for you.

Step 3

Add the baking soda. Sprinkle half the baking soda into the jar with the hot water. Stir the mixture to dissolve the baking soda in the water. Then, add the remaining baking soda 1 teaspoon (5 g) at a time, stirring each time to dissolve the baking soda.Continue adding baking soda until no more will dissolve in the water and a thin layer of powder forms on the bottom of the jar.You may need to add slightly more or less baking soda than the ¼ cup (55 g) to completely saturate the water.

Step 4

Cool and divide the water. When the water won’t absorb any more baking soda, set it aside to cool for about 20 minutes. Once the solution has cooled, divide it equally between two small jars or glasses.Leave the last bit of solution in the original jar, and throw out the undissolved baking soda that’s settled on the bottom.

Step 5

Separate the jars. Select a flat surface where you can leave the jars undisturbed for about a week. Good places include a work table or counter. Place the jars on the table or counter about 6 inches (15 cm) apart from each other. Place a plate between the jars to catch any water that may drip.The crystals will need several days to grow, and you don’t want to move them once they start growing. That’s why it’s important to find a place now where you can set up the experiment.

Step 6

Color the water. To make colored baking soda crystals, you can add five to 10 drops of food coloring to each jar. Stir the solution to mix the color into it. You can make both jars the same color, or you can color each solution a different color.If you make each jar a different color, half your crystals will be one color, and the other half will be another color.

Step 7

Cut a piece of string. Baking soda crystals need a medium to form on, and string is great for this. Any type of fabric string will work, like string, twine, or yarn. Use scissors to cut a foot-long (30-cm) length of string.Always be very careful when using scissors, and make sure you have adult supervision when cutting or using sharp tools.

Step 8

Tie weights to the string. To keep the strings weighted in the baking soda solution, you can tie weights to each end of the string. Good weights include beads and paper clips. Run each end of the string through the hole in a bead or end of a paper clip, and tie a small knot in the string to secure it to the weight.

Step 9

Place one end of the string in each jar of water. Take one end of the string and gently drop the weight into one of the jars. Pick up the other end of the string and drop the weighted end into the other jar. The string running between the two jars should be loose and hanging down slightly, like a smile.