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"Let us strive to make each moment beautiful."
Saint Francis DeSales
painting by Katie Bergenholtz

The Toothpaste Millionaire and Making Your Own Toothpaste



We are enjoying reading The Toothpaste Millionaire, by Jean Merrill; Rufus and Kate prove that you are never too young to have good ideas or succeed in business. Together they develop a simple recipe for toothpaste, manufacture, market, and sell their product and make millions -all before the eighth grade!
A great activity to go with this book is making your own toothpaste! Provide your students with these ingredients:

  • calcium carbonate
  • a mixture of 3 parts baking soda to 1 part salt 
  • glycerin
  • soap (Ivory Snow)
Have them test the ingredients for:

  • their texture
  • their ability to create suds
  • taste
and have them record the results on a scale from 1-5 (1 being the least and 5 the most). We had a wide variance in the outcome of these tests, which goes to show you that different people look for different things in their toothpaste and have different tastes.

 










The last test for toothpaste ingredients is a test for cleaning ability. Stain some tiles (the kind you use in bathrooms- you can get them at a hardware store) with some blueberry syrup and then use the different materials to test how well they cleaned the stains. We found that they all cleaned well but soap and calcium carbonate tied for first place, with baking soda and salt in second place.

Now that your students have all the test results in for texture, suds, taste and cleaning ability, they can decide how much of each ingredient to add to their own toothpaste formulas.



Your students now have to choose how much of each ingredient to add, based on the testing they have done. Each ingredient (calcium carbonate, a mixture of 3 parts baking soda to 1 part salt, glycerin and soap {Ivory Snow}) has strengths and weaknesses and they have to choose how much of each ingredient to add based on which qualities (taste, texture, sudsing ability, cleaning ability) meant the most to them. They also have a lot of flavors to choose from. We just used regular McCormick's flavorings (coconut, cinnamon, peppermint, lemon, vanilla, chocolate to name a few). No sweeteners of any kind were added.

Quentin writes down what he has put in.

Sam decides how much to add.

Katie mixes her formula.

Alex adds water to his mixture.

Quentin product tests.
All activities and photos are from 5/2008

The results we had were that none of them were ready to turn in the store bought toothpaste for their own creations, but they had a better understanding about what factors go into making a good toothpaste.


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2 comments:

  1. This is awesome! I've been eyeing the same book for a long time, but your lesson plan is just terrific!

    ReplyDelete
  2. I can just imagine trying to convince my kids to try something they put soap into......

    ReplyDelete

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