Elementary Science: Reflections on Food Chemistry

My elementary class that is studying food chemistry is approaching the end of the unit.  The students learned to test foods for starch, glucose, protein, and fat.  They built paper molecules showing highly simplified structures for each of these types of molecule and they wrote short essays talking about what foods they would bring with them on a trip to space.

Overall, it’s been a satisfying unit.  The children loved doing the chemical tests and they learned that scientists have to use different tests to find out different information about substances.  They had a lot of fun building the molecules and it gave them needed practice with fine motor skills (a big portion of the class has difficulty using tape).  More importantly, it helped them begin to understand that “protein”, “carbohydrate”, and “fat” are broad categories that each have many different items in them.

Unfortunately, many of the students still hold some substantial misconceptions.  I think the most pervasive misconception is that “protein” is a synonym for “all that is good in the world.”  For example, yesterday one of the children said that she thought the word vitamin meant “something that has a lot of protein.”  We talked about it, and I am pretty sure that no one holds that particular belief any more, but the underlying misconception is still present.

Homeschool classes have a different structure from traditional schooling in many ways.  For example, when I advertised this class, I very specifically told parents that we would do a 10 week* unit called Microworlds (done), a 10 week unit on Food Chemistry (in process), and a 10 week unit on Geology (upcoming).  Because of this set-up, I feel locked into moving on to our next unit two weeks from now, although I think the students would benefit from a longer exploration of food.  (Would parents actually mind if I re-arranged the timing of units a bit?  Most of them wouldn’t, but one parent in particular is eager for us to move on to geology, and with even one parent who wants me to stick with what I advertised, I feel that I don’t have much choice in the matter.)

If I teach an elementary unit about food in the future, I’d like to extend it to include all of the following:

  • Discussing what the main macro-nutrients are and doing chemical tests for starch, glucose, protein, and fat (included in this unit).
  • Discussing what calories are and measuring calories in some dry foods (not included in this unit).
  • Simple molecular modeling of starch, several sugars, protein, and fat (included in this unit).
  • Growing vegetables and using them to prepare an end-of-unit salad.  I might combine this with a wonderful secret salad dressing activity I read about in Liquid Explorations by LHS GEMS (not included in this unit).
  • Exploring foods that families from around the world eat using the book Hungry World (not included in this unit).
  • Learning how to read nutrition labels (not included in this unit).  (This would be a great way to include rich and authentic math activities in science.  However, I’d want to be very careful about not introducing or reinforcing obsessiveness about individual nutrients.)
  • Researching the history of how scientists have learned about nutrition.  I’d like students to learn about Alexis St. Martin and William Beaumont and the long search to discover how to prevent scurvy (not included in this unit).
Photos downloaded June292015 003
My trusty lightbox.  Here it’s being used for a high school transpiration experiment, but it’s just about big enough to grow a small, but reasonable, serving of greens for 10-12 children. 

*These may sound like enormously long units for elementary school, but we only meet once per week, for 1.5 hours at a time, so the units are actually not very long.

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