For this week’s #throwbackthursday post, I am sharing part of a post I wrote back in January 2013 highlighting an activity I did with my Algebra students involving making laundry soap on the cheap.
Each kid went home with a baggie full of homemade soap and a mind full of fractions, decimals and questions to ask about why they use the things they use in their homes on an everyday basis. For me, this activity was born from the idea that I was spending too much on laundry soap! My best friend found a recipe online titled “MAKE A YEAR’S WORTH OF LAUNDRY SOAP FOR $30.00!” and the rest, as they say, is history.
I have shared this recipe with everyone I knew because it was so easy to make, it was so inexpensive, and it was just amazing to replace something that I mindlessly spent hundreds of dollars a year on when it was unnecessary. Here’s how I adapted it into an amazing classroom activity:
We took the recipe with ingredients of given weights in ounces. In order to make three batches of the soap with my ingredients (for three classes) we divided each weight by three, introducing fractions into the activity, and measuring everything out. The entire class participated in this activity by physically measuring the ingredients, calculating how much to add and even performing additional operations to make up for measuring mistakes. Measurement is not only a big part of the Geometry curriculum, but it is also a major weakness for most of the students I’ve taught. After making the soap, we engaged in a discussion where we compared the price of our soap to the price of store-bought soap–especially the super-expensive “pods” that seem to be gaining popularity. At the conclusion of the activity, I had the students write reflections on what they learned. Overwhelmingly, the students expressed that they enjoyed the activity and wished that they had the chance to do math in this way more often. We also watched a documentary on Netflix called Chemerical, which follows a family of five who commits to ridding their home of all chemical cleaners to replace them with homemade cleaners made with simple, inexpensive ingredients like baking soda and vinegar.