Unit 2: From Farm to Fridge

Lesson 1: Eating with the Seasons

Grade Level: Sixth Grade

Time Required: 60 minutes

This lesson is most effective after Willow Bend’s 6th grade program called “Food and Fossil Fuels”. In this timely and proactive program, students explore the often unexplored world of fossil fuels use in food production. Suggested follow-up fieldtrip “Healthy Body, Healthy Earth Fieldtrip” at Willow Bend.

Primary AZ State Standards:

(Cross-reference “Standards Matrix” for full listing)

Science:

S06-S5C3-04: Explain how thermal energy (heat energy) can be transferred by conduction, convection, radiation.

Social Studies:

SS06- S1C2-02: Describe how farming methods led to the development of cultures and civilizations from hunting and gathering societies.

Objective(s):

Students will list foods which are available locally in different seasons.

Students will describe and compare methods of food preservation including refrigeration, drying, and canning.

Students will construct their own food dehydrator and dehydrate food.

Students will describe how farming methods and food storage needs helped civilizations form.

Background Information:

For teachers not familiar with CSA’s (Community Support Agriculture Projects), here is a short write up by our Flagstaff CSA (

“What is Community Supported Agriculture?

Community Supported Agriculture is a direct connection between a local farmer and the people who eat the food they produce. At the core of CSA is mutual commitment: communities of eaters commit to supporting a local farmer for a season. In return, CSA participants receive fresh, seasonal produce—sharing in the inherent risks and the bountiful benefits of farming.

Community Supported Agriculture: An Alternative

CSAs provide an alternative model to our current system of agriculture. We’ve all purchased vegetables from the piles of flawless produce at the grocery store. But do we know where that food comes from? What country was that tasteless winter tomato grown in? Who grew that tomato? Does it contain genetically modified organisms? It is usually impossible to answer these questions, to trace our vegetables from farm to table. But CSAs can reconnect us with our food—providing a tangible, hopeful solution. CSAs promote fair wages for farm workers, environmental stewardship, economic sustainability, and strong communities.”

CSA’s function by having community members buy “shares” at the beginning of the season, thus giving the farmer stable capital resources to work with throughout the season. Each week, the farmer delivers food to be distributed to the CSA community members. If the season is particularly bountiful, CSA community members reap the profit. If the season is difficult for the farmer, then the CSA community members help shoulder the burden. In this way, the community helps ameliorate some of the risk of farming, support local economies, reduce the use of fossil fuels associated with food distribution, and enjoy delicious, locally grown food! The farmers benefit by having a source of stable income associated with the local community.

The Flagstaff Community Farmers’ Market is another place where people in the Flagstaff community can buy locally grown food. The Flagstaff Community Farmers’ Market grew out of a vision by City Councilman Art Babbott and has been growing since its inception in 2001. Below is a description of the market’s vision from their home page (

“TheFlagstaffCommunity Market (FCM) is a regional producers market that operates for growers and producers of agricultural and related products. The primary purpose of the Market is to support small and medium sized independent growers and producers by providing citizens with a local alternative to corporate and globalized food production.
It is our intent to connect growers and consumers and encourage people, both urban and rural, in growing more of their own food. A secondary purpose is to provide an outlet for small-scale producers of value added food products, local artisans, and community and sustainable agricultural groups.
Additionally, it is the purpose of the Community Farmers Market to provide a Community gathering space for residents and visitors toFlagstaffto mix in a relaxed, educational, and fun environment.”

The goal of this lesson is to get students thinking about locally available produce, the seasonality of produce, and the energy required to obtain and store these foods. In particular, students will think about how agricultural methods and technology has changed hunter-gather societies to established civilizations over time. Then, they will build a food dehydrator, reinforcing the sixth grade standards in which students learn about the transfer of thermal energy through conduction, convection, and radiation.

Pre-lesson Preparation:

  1. Gather materials listed.
  2. Regarding food to dehydrate, this can be as simple as cutting up some tomatoes, squash, or fruit ahead of time, or making a more elaborate concoction such as fruit leathers. Recipes can be found on websites such as:

Activity Instructions:

Listing locally available seasonal foods

Whole class, small groups

15minutes

(adapted with permission from “Harvest of History” Lesson Plan: Module 3, Activity 2 “Cycle of Seasons — Impact of Technology on Seasonal Foods”. See Resources.)

  1. Distribute local grocery flyers. Ask students to describe where all the different produce products come from. If applicable, review ideas from Food and Fossil Fuels lesson (Willow Bend), especially concepts of food miles.
  2. Ask students, “Why kinds of foods would you be eating if could only eat food grown in Arizona? Why is eating locally a good thing?”
  3. Talk about local CSA and Flagstaff Community Farmers’ Market. Ask students if anyone belongs to the CSA or has visited the Flagstaff Community Farmers’ Market. Also remind students that the best locally and seasonally available food is food you grow in your own garden!
  4. Explain that as a class, we are going to come up with a list of foods that are seasonally available here in Arizona.
  5. Divide class into groups, group size depending on the number of newsletters printed off from the CSA website
  6. Put butcher paper chart, divided into months of the year, in front of class.
  7. Hand out CSA newsletters and blank paper to each group.
  8. Tell students to look at the side of the newsletter and make a list of products that are available in their month. Divide them into fresh and preserved.
  9. Have the group beginning with January write their products, starting with fresh products, on the chart.
  10. Each group that adds should only write new products available. For products continuing from the month before, simply continue and arrow through their month (see example below).

Jan / Feb / Mar
lettuce
peas
rhubarb / Apr
/ May / June / July / Aug / Sept / Oct / Nov / Dec
  1. Ask students to think about if this chart actually reflects what they eat and when. If not, why not? Our food comes from all over the world, and we have refrigerators!

The society and food timeline

Whole class, partners

15 minutes

  1. Put students in pairs. Give each pair a piece of paper and some markers.
  2. Tell students, “With your partner, think about how societies have changed as a result of changes in food sources and food preservation. Create a timeline that reflects the major changes.”
  3. Give students about 10 minutes to work.
  4. Discuss the timelines with the class. Be sure to mention that:
  1. Hunter-gatherers were more nomadic and had to follow food sources. They also had to carry their food, so couldn’t produce a lot of excess.
  2. Early civilizations formed as a result of agriculture and being tied more closely to the land.
  3. Methods of food preservation before refrigeration included drying or storing food underground in root cellars or in caves. Some food, such as meat, was preserved with locally available mineral salts. These methods are still used today, though there are many challenges with using these methods (rodents, bugs, mold, having place to store and process food).
  4. Refrigeration, invented in 1876 by Carl Paul Gottfried von Linde, allowed produce to be shipped all over the world in refrigerated containers, stored in refrigerated display cases in stores, and kept in people’s individual refrigerators at home. Freezing also allowed for even more long-term storage of food.
  1. Tell students to imagine they were early pioneers in Arizona.
  2. Ask students, “Which method of food preservation would you use? (drying) Which of the seasonal produce listed on the chart do you think you could preserve that way?”
  3. Have students discuss how the different types of foods could be preserved. For example, squash and tomatoes could be dried, but watermelon could not!
  4. Tell students, “Some Hopi families have special rock houses used just for drying and storing produce such as corn. Today, you are going to get to build a devise for drying food. Does anyone know what that is called?” A food dehydrator. Discuss the vocabulary term by breaking it down into word parts (de-hydrat-or).

Building a dehydrator

Three groups

35 minutes (or more, depending on time available)

  1. Explain to students that we are building a dehydrator with a pretty simple design. There are commercial dehydrators available that work with electricity.
  2. Ask students, “If we aren’t using electricity, how do we get this dehydrator to work?” Solar, heat energy. In Arizona, we also have natural aridity to help the process.
  3. Ask students, “Can anyone explain the terms conduction, convection, and radiation?”

Conduction is the transfer of heat energy through direct contact with a conductive material, like the metal of a frying pan.

Convection is the transfer of heat energy through the movement of liquids and gases.

Radiation is the transfer of heat energy by electromagnetic waves coming from the sun.

  1. Tell students to think about these processes as we are building the dehydrator. Will ask student which processes are working to dehydrate the food.
  2. Divide class into smaller groups if possible, depending on availability of materials.
  3. Model steps for students as to how to build the dehydrator.

Each group needs:

  1. A cardboard box
  2. A ruler
  3. Black construction paper
  4. Glue & tape
  5. Scissors
  6. 3 wooden dowels
  7. A thermometer
  8. Plastic wrap
  9. A piece of plastic, needlepoint mesh
  10. Food to dehydrate (moister foods will take longer)

Food Dehydrator instructions reprinted from KidsGardening Website, with permission.

Constructing a Simple Food Dehydrator
It can take 3 to 4 days of hot, dry weather (85° F and humidity below 60 percent) to dehydrate a juicy vegetable like a tomato.* If you live in an area with cool and/or humid summers, you're better off finding a design that generates extra heat and air flow or purchasing a commercial dehydrator. Try to involve your class as much as is reasonable in the planning and building process.

  1. Measure 8 inches up from the bottom of your cardboard box and draw a level line across the front. Draw a line along the sides from your first line up to the back of the box and then cut along them as shown. Glue pieces of black construction paper to the inside surfaces.
  1. Cut a hatch about 6 inches square in the back for access and use a piece of tape to stabilize the door as illustrated. To enable air flow, poke vent holes in the sides and bottom.
  1. Cut your dowels slightly longer than the length of the box. Make holes about 8 inches up from the bottom in the ends of the box to fit the dowels tightly, and slide them through. Wash and dry the needlepoint mesh or plastic grid, cut it to fit if necessary, and set it on the dowels.
  2. Tape the thermometer to the inside wall of the dehydrator. Cover the top angled face of the box with plastic food wrap and tape it in place.
  3. Place your prepared fruit, vegetable, or herbs onto the mesh tray via the back hatch, andclose it securely to prevent insects from entering. Prop up the dehydrator on boards or other supports so air can enter through the holes in the bottom. (If insects find their way into the dryer, you can cut a piece of cheesecloth or window screen and tape it over the holes on the outside of the box.)
  4. Face the dehydrator into the sun, turning it several times a day to capture the most directrays. (This offers a great opportunity for lessons on the sun's angles and Earth's movements.) Move the dehydrator inside at night.
  5. Have students keep track of the inside temperature and stir the food occasionally to speed drying. They should observe the produce daily and note changes in characteristics such as color, texture, and odor.
    *Temperatures inside a food dryer should be at least 95° F for drying herbs and edible flowers and120° Fto140° Ffor drying vegetables and fruits.
  1. While students are working, ask them to think about the heat transfer processes at work. Radiation is at work because the box is heating up with direct contact with the sun’s rays. The black paper increases this rate of transfer. Convection is also playing a part as the air inside circulates through the plastic mesh, heating up and drying the food. The only process not in effect is conduction.
  2. Food may process in anywhere from 1 – 7 days, depending on the food. Have students check the food frequently, moving food around to make sure it gets evenly dried. Students might also be asked to keep a journal, observing the color and texture of food, how long it took to dry, and the temperatures inside the box.
  3. In conclusion, ask students how dehydrating food would help them as pioneers in Arizona.

Resources:

Cycle of Season – Impact of Technology on Seasonal Foods.Lesson Plan: Module 3,

Activity.Harvest of History website. Accessed on July 9, 2010 from

Drying fruit leathers.Pleasant Hill Grain website. Accessed July 9, 2010 from

Flagstaff Community Supported Agriculture website. Accessed July 9, 2010 from

Flagstaff Community Farmers’ Market website. Accessed July 9, 2010 from

Fruit leather and fruit roll-up recipes. Everything Kitchen website. Accessed July 9,

2010 from

Preserving the Harvest: Constructing a Simple Food Dehydrator. National Gardening

Association: Kids Gardening Website. Accessed July 9, 2010 from