Science Activity: Making a Terrific Toothpaste

1. Get Ready    

Package of unflavored Tums antacid tablets
Small box of baking soda Assorted liquid food colors
Assorted liquid food flavors (for example, vanilla and orange)
Plastic spoon
Measuring spoons
Two sandwich bags
Clean dish towel
Two clean, clear, plastic cups
Rolling pin
Access to water

2. Do and Wonder 

Toothpaste Recipe

To begin, you'll need to grind up some Tums to form a fine powder. Put two or three in the sandwich bag, and then seal it tightly. Break up the Tums by tapping on them through the bag. When they're in pieces, put the towel over the bag and then move the rolling pin back and forth over it, crushing the Tums into a fine powder. Keep adding, breaking, and crushing Tums like this until you've made about 1/2 teaspoon of powder.

Put the powder into a plastic cup, and add 1/4 teaspoon of baking soda. Then mix in two or three drops of water to make a paste.

You've made your own toothpaste! Write down your obser­vations. What does it taste like? What does it smell like? What is its texture like?

Your Improved Toothpaste Recipe

Study the original recipe and your observations to get ideas for improving the toothpaste. Think about using different amounts of substances, adding a flavor, and changing the color.

Make a new batch of toothpaste, test it, and write down your observations.

3. Think and Write

In a short paragraph, compare the original toothpaste you made with your own improved brand. How are they similar and different?

In another paragraph, make a hypothesis that explains why toothpaste makers limit the amount of grinding material (called an abrasive) used in their products.

Explanation

Toothpaste is made of a combination of substances. It usually contains a fine material, called an abrasive, that grinds and pushes deposits of plaque and tartar off your teeth. Some toothpastes also contain fluoride, which helps prevent holes called cavities from developing in your teeth. In addition, toothpastes usually contain a little soap along with a flavor and a color. The simple toothpaste you made used calcium carbonate (from the Tums) as an abrasive and baking soda to remove stains and reduce mouth acids.