This is a two class periods long activity for 6-8 graders.

 

OBJECTIVE:

Students will understand the following:

1. Bees use the pollen from flowers as food.

2. When they land on flowers to collect pollen, they spread pollen from one flower to another.

3. Many plants cannot grow unless they are cross-pollinated by insects such as bees.

4. Because bees cross-pollinate so many fruit and vegetable plants, they play a vital role in food production all over the world.

 

MATERIAL:

•Computer with Internet access

•Five healthy young patio tomato plants in pots (plants must have no blossoms)

•Cotton swabs

 

PROCEDURE:

1. Review with your students what they have learned about bees. Make sure they understand that bees use the pollen from flowers as food, and that, when bees land on flowers to collect pollen, they spread pollen from one flower to another.

2. Tell the class that bees play a very important role in food production all over the world, and ask students if they can explain this fact. Tell students they are going to perform an experiment that will help them find the explanation or confirm the one they have given.

3. Display the five plants for the class, telling students that they are tomato plants that have not yet blossomed. Make sure students understand that each fruit of a plant, in this case, each tomato, grows from the base of the blossom. Students should also know that many vegetables, such as squash, cucumbers, and peppers, are really considered fruits, since they grow from the blossoms of plants.

4. Divide your class into groups, challenging each group to use the five plants to design an experiment that will answer the question, “How do bees aid in the production of fruits and vegetables?” After reminding students of the requirements for a valid scientific experiment, have groups write up their experimental designs.

5. Have groups share the experiments they have designed. Then help students refine their experimental designs until you and the class arrive at the following steps:

1. Label the pots numbers 1, 2, 3, 4, and 5.
2. Place plants 1, 2, 3, and 4 near or in a south-facing window.
3. Separate plant 5 from the rest, but be sure it gets the same amount of light as the others. (Plant 5 will be the control.) Don’t let any of the plants get too hot or too cold.
4. After a few weeks, when all the plants have a fair number of flowers, use the same cotton swab to gently tease open all the flower tips on plants 1, 2, and 3.
5. Gently rub the swab over the tip of each flower. (The cotton swab represents a bee moving from flower to flower.)
6. Use a separate swab for plant 4, being sure to tease all the flowers.
7. Don’t do anything to plant 5—the control plant.
8. Continue teasing plants 1, 2, 3, and 4, observing the plants daily until you see marked changes.
9. Describe the similarities and differences between the control plant (plant 5) and the pollinated plants (plants 1, 2, 3, and 4). Are there any differences between the three cross-pollinated plants (plants 1, 2, and 3) and the plant that was pollinated only with its own flowers (plant 4)?

6. Have all students participate in carrying out the experiment.

7. When the experiment is complete, have each student write up a “lab report,” describing the results of the experiment and explaining the conclusions that can be drawn from the experiment regarding the importance of bees in the growing of fruits and vegetables.

 

DISCUSSION:

1. Describe a beeless Earth.

2. How is a bee society like a human society?

3. Explain the process of replacing an African queen bee with a gentler variety.

4. What do you think would have happened if the killer bees hadn’t escaped?

5. Develop a method to reduce the likelihood of a killer bee attack.

6. Is increased honey production worth the risk of importing potentially dangerous insects?

 

EVALUATION:

You can evaluate groups on their lab reports using the following three-point rubric:

Three points: clearly and completely describes each step of the experiment; clearly and completely describes the results of the experiment; includes well-written and well-reasoned conclusion regarding the importance of bees in fruit and vegetable production

Two points: adequately describes each step of the experiment; adequately describes the results of the experiment; includes a satisfactory conclusion regarding the importance of bees in fruit and vegetable production

One point: unclear and/or incomplete description of the experiment; unclear and/or incomplete description of the results of the experiment; conclusion vague or missing

You can ask your students to contribute to the assessment rubric by determining the number of experimental steps to be described.