We started with David Michell's The Wonders of Waldorf Chemistry (this book is also available for free as a PDF from The Online Waldorf Library).
He has information on Fats & Oils at the seventh grade level ("Oils and Fats," page 155) and the eighth grade level ("Fats, Oils, and Waxes," page 218).
We did the Fat Test. Open up a brown paper grocery bag and cut off one of the large sides and lay it flat. Then simply trace a number of circles on the brown paper (we used one of the small wooden rainbow bowls from Grimm's and traced it nine times) and place a sample of a variety of foods on the paper, one in each circle. I let the girls wander around the kitchen and decide what they wanted to test. They chose things like a potato chip, butter, bread, an apple slice, a fruit candy, boxed cereal flakes, chocolate pudding, etc. By the end of our session, the fat had already spead and left its telltale stain.
Then I read them some information on surprising products which are not vegan because of the use of beef fat (stearic acid) in them, like Crayola crayons. The slip agent in grocery store plastic bags (8 Unexpected Items That Contain Animal By-Products) was the one that surprised and grossed me out the most. Stearic acid is not always synonymous with beef fat, I will point out, but it is much more abundant in animal fat than in vegetable fat. If you're vegan it's on the list of products to avoid unless the product label specifically says that it is from a non-animal source.
Next up, making towers of Crisco (fat) and sugar cubes (sugar) on paper plates to reflect the amount of each found in some foods on the menu at McDonald's. I had the girls name some foods they might order if they went to a McDonald's and we wrote them on 3x5 index cards. Then we looked up the nutrition information (you can download McDonald's Nutrition Facts FREE from Teachers Pay Teachers in a nice PDF) and wrote the fat and sugar on each index card, got out our kitchen scale, and went to work. It will save you some time to only weigh the Crisco out. Sugar cubes weigh 2 grams each and so that tower can be easily calculated. Place the index card by each paper plate and you have a compelling visual! Here's what they picked:
6 grams sugar, 9 grams fat
double quarter pounder w/cheese
9 grams sugar, 42 grams fat
9 grams sugar, 29 grams fat
0 grams sugar, 19 grams fat
86 grams sugar, 0 grams fat
There are lots of food label scavenger hunt activity options but we used another FREE TpT product, Food Label Scavenger Hunt. This requires either buying the foods in question or printing off the full color pictures of the food labels. I chose to buy the foods.
We threw away the sugar free chocolate pudding afterwards, because it was full of really dangerous aritifical sweeteners. Some of the foods we sent to a church activity for teens and some we kept for ourselves to eat. One of the things we kept was the Hot Pockets. This is a Twinkie-situation. My girls never had one, and always wanted to try one, and one day I had a friend give them a Twinkie and they were completely revolted by it. My girls relived the same experience with the Hot Pockets. They were so excited and then they could barely eat it. I asked Becca what she thought and she told me that she couldn't even finish it. I asked her why and she said it was because they read the nutrition label. Then she told me, "I ate a carrot afterwards because I wanted to have something real."
When I asked the girls what they observed after reading all those nutrition labels, they talked about portion size manipulation so that a food will appear healthier. They also noticed how the packaging would highlight all of the good things about a food and leave off all the not-so-good things. I also explained to them about how a nutrition label lists items in order, but that if sugar is found in more than one form, those things can be listed separately, which serves to move the sugar lower down on the label (evaporated cane juice crystals, corn syrup, sugar, honey, etc.). If they were all combined into SUGAR, the percentage of it in the food would be much higher in the list.
If you want a really long scavenger hunt, there's a nice one on pages 18-19 of Food Label Reading Lesson: "Is This Product Healthy?", which is also available for FREE from TpT. However, we had to break this up into two trips last year because it took forever. The best part of it, though, was calculating what percentage of each breakfast cereal was sugar. That's an eye-opening experience! So I showed the girls yesterday how to do it. Just take the number of grams of sugar in a serving and divide it by the number of grams in the serving size. Convert the decimal to a percentage and there you have it! We wrote each cereal's sugar percentage on the box in red Sharpie.
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