Teaching kid about science with gravy

It is Thanksgiving time – learn how holiday favorites such as mashed potatoes and gravy can help teach kids about science.

Gravy is the delightful topping that covers the meat, potatoes and dressing at a holiday meal. But did you know there is science behind it?

Science isn’t about knowing the answers; it is about a process of discovering answers on your own. Are all gravies the same? How can you make it better? These types of questions may lead to more questions and experimentation. Explore the science of your Thanksgiving favorite using the ideas and questions below. You’ll notice I haven’t provided many answers – you get to have the joy of discovery on your own!

  1. Explore the characteristics of gravy. How do you like it? What color should it be? How thick should it be? What should it feel like on your tongue? Should it be sweet at all? How salty should it be?
  2. Gravy is made using one of many types of thickeners. The most common are flour and cornstarch but arrowroot, instant mashed potatoes, rice flour and even tapioca can be used. What are the advantages of the different types of thickeners?
  3. Experiment with making your own gravy: start with a flavorful liquid as the base. Using stock made from a chicken or turkey carcass can be a great start to your gravy. You can also use canned stock, the liquid from the bottom of the roasting pan or a mixture. How does the stuff in the bottom of the pan taste? Why does it taste different? The little brown bits at the bottom of the pan are the result of the Maillard reaction, which gives many foods their flavor. Scrape off as much as you can before making your gravy. What do you think will do the best job of removing the browned bits without ruining the flavor? Hot water or cold water? Would a something acidic like lemon juice help or would that ruin the flavor? What about scrubbing it with vegetables?
  4. The next step in making your gravy is using a thickener, such as flour. Try tasting raw flour. How does it taste, is it different from cooked flour? Why does it taste different? Try adding a small bit of flour to your stock and see how it tastes. It will probably have a paste-like flavor. Usually gravies are made by creating a roux, which is flour cooked in fat. Heat some fat (pan drippings, oil, butter, bacon grease) in the bottom of the pan and add flour. What do you think this will do to the taste of the flour? After a few minutes, notice the difference in color and taste. Keep cooking the roux and notice how the color and flavor changes over time. How long do you think you should cook the roux before adding the liquid? Do you think the cooking time will affect the thickening power? Will it make a difference if you add the liquid to the roux or the roux to the liquid? Should the liquid be cold or hot? Does it matter?
  5. For another experiment, you can try adding flour directly to the liquid and in another pot, adding roux. What do you think the difference will be? Experiment and find out.
  6. Cornstarch can also be used to thicken gravy. How will cornstarch be different from a roux? Notices the differences in texture between cornstarch and flour. Compare the tastes in the raw materials. Try using the same amount of flour and cornstarch in a liquid. Does one thicken more than another? Is the color different? Why is flour usually made into a roux but cornstarch is not? If you cook cornstarch in fat, will it change the flavor or thickening power?

Michigan State University Extension recognizes there are many opportunities for science education that occur in the natural world, including this one with gravy. This lesson can be conducted by any group working with children, including families, day cares, schools or 4-H clubs. Have fun experimenting and try to make the ultimate gravy for your Thanksgiving meal!

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