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Hotchalk Global

news & tips

A collection of helpful articles on teachers and teaching

Energy from Cow to Hamburger

A wonderful test item from way back in the 80’s asked the students to track the energy of a hamburger from grass to cow to plate. It seems pretty straightforward but takes a lot of science thinking to explain fully. Food is always a fascinating science topic.

There is a new television series titled DooF (food spelled backwards). Their website has a lot of good materials for a unit of study on food for lower elementary levels. Most of the materials online are for 3rd grade and higher.

The first question in my nutrition unit is “where does our food come from?”  Most of my kids are from the Midwest and still have some connection to the land and agriculture. Most have seen cattle and pigs and crops growing. Still, I am amazed at how little even these connected kids know about the food they eat.
A cow has to be fed grain or grass. Cattle are designed to eat grass but in modern times we feed them more grain to help produce the marbled tasty meat that matches the American palate. There is a large movement to eat more grass fed beef. It is leaner and when you do the energy accounting the grass comes out better than grain (it takes more energy pound for pound to grow grain). So, in that hamburger you ate this month where did the beef come from. Few of us have ever asked the local grocer that question. My kids asked the meat guy at the local store and he gave the students a wonderful story about meat and how it gets from field to table. Our meat came from Nebraska on that day.

The milk the students drink is also connected to cattle but what about the soda? In a can of coke there is sugar or corn syrup. Where does that come from? The question here on energy is that in accounting for the energy from field to plate we need to take into account the energy to transport sugar cane, sugar beets or corn syrup to the plant that makes the soda. Few of my students had ever considered the connection between soda and agriculture. Making high fructose corn syrup, like that in many sodas, is an energy intensive process. This in itself could be a unit of study. The details can be found here:

My students eat a lot of pasta. Now there is something they know is connected to agriculture but they are not certain if it is corn, rice or wheat that makes up the thin white spaghetti. A good Wikipedia post exists on this topic.

To track the connections and energy with a simple bowl of spaghetti may take a group effort. The tomatoes do not generally come from somewhere close. Florida and California produce a lot of tomatoes but some come from as far away as South America. In fact the tomato is believed to have originated in South America.
There are herbs and spices in most sauces. Students can research basil, oregano, salt, pepper and garlic. When you begin to analyze the myriad of stuff that goes into a simple dish you may be, like me, amazed that it all comes together.

My Grandmother used to grow and can most of her own vegetables and dry her spices. We had potatoes, carrots, squash and apples in a root cellar. We had tomatoes and tomato sauce and salsa from our garden in glass jars lining the pantry. Today we mostly go and grab a can or jar of spaghetti sauce from the store. Understanding how much goes into processing that food not only produces appreciation for the process but a scientific understanding of the energy costs. It is tough to can your own food but a lesson in canning in your classroom taught by a local gardener would be an amazing experience for your kids.
During World War II the US government encouraged citizens to plant victory gardens. Eleanor Roosevelt planted one at the White House. Decades later First Lady Michele Obama planted a garden there as well.

Now this is a great idea. There is a whole movement that encourages people to eat locally grown food in season. Watching the White House Garden was popular in 2009 and may be on the agenda again. If so it would be worth a mention in a foods unit.
No foods unit would be worth its calories if the kids did not get a chance to cook and eat some of the study materials. There are lots of interesting recipes on the DooF web site to try that involve little or no cooking.
The last piece is food safety. Here some of the science turns critical. Why can’t you eat mayonnaise that has been left in the warm sun? Can raw chicken hurt you? Here the science of bacteria can be center stage and engaging. One of the best sites I found comes from Iowa State.

From the USDA you can get food safety materials in English and in Spanish.

A food safety detective game rounds out the field of exceptional materials.

I will admit that the journey is a bit of a ramble. The students should develop a bit deeper knowledge about how energy transfers through a system of producers and consumers. The energy costs that are not accounted for, such as transportation, can be included in an upper level lesson. The most important part of the lesson may be the safety portion. Safety is the job of the USDE. However, one of my students recently observed that if the food comes from far away we may not have as much control over safety as we do when it is grown and processed closer. Now that is a big idea.

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