Using tomatoes as a theme, students practice the math and science skills of estimating, measuring, counting, graphing and sequencing. Grades K-2
life cycle: the stages a living thing goes through in its lifetime
tomato: a glossy red, or occasionally yellow, pulpy edible fruit that is typically eaten as a vegetable or in a salad
Did You Know?
- Large quantities of tomatoes are weighed by subtracting the weight of the trailer from the total weight of the tomatoes and the trailer. A tomato truck can hold 50,000 pounds of tomatoes, which is about 300,000 tomatoes.1
- Seeds are the beginning of a new tomato plant. In a setting undisturbed by humans, the tomatoes would fall to the ground. Only if the conditions are right for growth will a tomato seed grow into a plant and the more seeds a fruit has, the better chance there is for a particular tomato species to survive. However, scientists and farmers are working together to genetically reduce the number of seeds tomatoes produce so that people can enjoy more of the "fleshy" part of the tomato rather than the seeds.
- The United States is second to China in the production of tomatoes while California and Florida are the two leading states for fresh market usage of tomatoes.2
Background Agricultural Connections
Tomatoes are scientifically classified as a fruit because they develop from a flower and have seeds. However, many people view them as a vegetable because they are used in cooking and food preparation more like a vegetable. Believe it or not, in 1893 the supreme court actually ruled tomatoes as a vegetable in the case of "Nix v. Hedden."
Tomatoes are usually grown from seed. Tomatoes are annual plants, which means they complete their life cycle in one season. They begin as seedlings, then grow into a bush or vine. Flowers then form, pollination occurs, and actual tomato begins to grow. There are many varieties of tomatoes which include differences in size, shape, and flavor.
Tomatoes are a common garden crop, but they are also grown commercially by farmers. Some tomatoes are sold to grocery stores, but a large portion of tomatoes are used to make ketchup, spaghetti sauce, tomato soup, pizza sauce, etc. When grown commercially, tomatoes are sorted by color as they are harvested by machines in the field. Most tomato harvesting machines use lasers to sort green tomatoes from the ripe red ones. The green tomatoes are pushed off of the harvester and are thrown back onto the ground for fertilizer. Tomatoes can also be handpicked for shape, size, color, and beauty.
Canning tomatoes have been specifically "designed" through selective hand-pollinating of desired tomatoes, to be "squarish" in shape (like a Roma tomato), so that they can be easily harvested with harvesting machines and packed more efficiently in tractor-trailers. The University of California at Davis is well known for its creation of the "square tomato."
Canning tomato growers have contracts with specific canning companies. The contract states what date the farmer must have a certain amount of tomatoes at the cannery. This is done so that the cannery is used efficiently and the tomatoes do not rot. Farmers must carefully plan the planting and watering of their fields so that their contract can be met.
- Print the KWHL Chart. This should be kept on chart paper so that it can be used and posted throughout the entire lesson. Ask students the following questions and place their answers in the first three columns. The fourth column will be filled in at the conclusion of Activity 3.
- What I know.
- What do you know about tomatoes?
- What color(s) are tomatoes?
- Where can you buy tomatoes?
- What foods do you eat that have tomatoes in them?
- What I want to know.
- Is a tomato a fruit or vegetable?
- What does a tomato grow from, a tree or a plant?
- How do tomatoes travel from the field, to the grocery store, and to your plate?
- How can I learn more about tomatoes?
- Where can I find information about tomatoes?
- Who can I ask about the life cycle of a tomato?
- What farmers in my hometown grow tomatoes?
- What I know.
- For a visual, have the students bring in labels of items they use at home that contain tomatoes such as ketchup, spaghetti sauce, salsa, tomato soup, etc. Make a collage of the labels in the shape of a tomato and post it next to the KWHL Chart as a resource.
Explore and Explain
Activity One: Language Arts
- Bring in several tomatoes of different sizes, varieties and ripeness.
- Have the students discuss the many properties of tomatoes. Examples include, color, size, shape, texture, etc.
- Have each student pick out two tomatoes (or divide the tomatoes into two groups) and orally state a sentence that compares the two tomatoes. For example, "This tomato is larger than that tomato."
- Next, tell the student to trade their two tomatoes with a student that sits to the right and state another sentence that compares the two new tomatoes. For example, "These two tomatoes are smaller than the first tomatoes I held in my hands."
- Ask the students to smell the tomatoes and state a sentence that describes what they smell.
- Refer back to the KWHL Chart and have students voluntarily add information to the third column. For example, in column three a student may respond by saying, "I can learn more about tomatoes by looking at them closely."
Activity Two: Math
Estimating, Weighing and Graphing
- Use the largest tomatoes you can find and have the students estimate the weight by guessing how many unifex cubes must go on one end of the scale to balance the tomato.
- Determine the actual number of unifex cubes needed to balance the scale.
- Make a bar graph of how many students guessed too many, too few or just the right amount of cubes.
Estimation and Length Measurement
- Using the same large size tomatoes have the students estimate the circumference of the tomato.
- Each student should be given a piece of yarn or string the length they think would fit exactly around the tomato.
- Determine the actual circumference of the tomato using yarn or string.
- Have the students physically compare their string to the "actual" string for the circumference.
- After making comparisons, each student will stand in the appropriate section of the room you have pre-labeled on a small size poster board; "String Too Short," "String Too Long," or "String Just Right."
- Have the students use their string and glue it to the poster in the shape of a tomato, each student can write their name in the middle for identification.
- Discuss with the students the difference in circumference when looking at the three posters.
Estimating and Counting
- Give each student 1/2 of a cherry tomato.
- Have the students examine the tomato and count the seeds in their 1/2 of the tomato.
- Discuss with the students, the purpose of seeds and why there are so many seeds in a tomato.
- Next, show the students a very large tomato.
- Using their experience of counting the seeds in a cherry tomato half, have the students estimate how many seeds there are in the big tomato.
- Cut open the tomato and have each student count a portion of the seeds.
- Demonstrate how addition is done, using a calculator, to determine the total number of seeds in the large tomato.
- Discuss the differences noticed in seed number, seed size and seed shape.
- Refer back to the KWHL Chart and have students voluntarily add information to the third column. For example, in column three a student may respond by saying, "I can learn more about tomatoes by estimating, counting, weighing, and graphing information about tomatoes."
Activity Three: Science
Sequencing, Predicting and Life Cycles
- Using the Tomato Life Cycle, have each student cut out the pictures of the tomato plant during different stages in its life.
- Have the students place the pictures in what they think is the correct order.
- Ask the students to glue the pictures on their paper and write their predictions under each one.
- Plant 8-10 tomato seeds (from a purchased packet-the seeds from a fresh tomato will not grow well)and watch the seeds develop into plants. It is helpful to keep a moist paper towel over the surface of your soil until the seeds sprout. The seeds will take 7-13 days to sprout.
- Have the students draw a picture or write down their observations from each day. They can compare their sequencing hypotheses with what actually happens to the seeds that you planted.
- Discuss the life cycle of the tomato from what they observed.
- Using the glued pictures and their drawings from the observations, have the students create a proper sequence of the tomato life cycle.
- Refer back to the KWHL Chart and have students voluntarily add information to the fourth column. For example, in column four a student may respond by saying, "I learned the correct steps of the tomato life cycle from planting a tomato seed in the classroom."
View the Tomato: How Does it Grow? video to learn more about how tomatoes are grown and harvested.
Invite a tomato farmer to your classroom. Have them discuss tomato farming.
Make homemade tomato sauce with your students. Have each student contribute one tomato to the sauce, measure the sauce and finally, enjoy it over noodles. Have the students predict how many cups of sauce the tomatoes will produce.
Have a local fast food restaurant donate one packet of ketchup to each of your students. Discuss the sequence of events that had to occur to make the ketchup. Enjoy the ketchup on sandwiches.
After conducting these activities, review and summarize the following agricultural literacy concepts:
- Farmers grow tomatoes for food. We eat them whole, or after they have been made into ketchup, tomato soup, spaghetti sauce, pizza sauce, and other food products.
- Tomatoes grow on plants.
- Tomatoes complete their life cycle in one growing season.
Special thanks to Kim Giese of the California Tomato Board for assisting in the development of this lesson.