This simulation helps students model and understand the conditions that trees need to live and grow.

#### Time Considerations

50 minutes

#### Materials

- 8″ x 10″ pieces of paper or paper plates
- Small squares of blue and yellow paper, or colored math cubes
- Markers or crayons
- Optional: “tree cookies” (tree trunk or branch cross-sections showing annual growth rings, often available from tree-trimming services)

#### Key Vocabulary

water, sunlight, growth, growth rings, competition, strong, weak, healthy, stressed

#### Getting Ready

- Cut 3″ x 3″ squares out of blue and yellow construction paper. To save time, you could use colored math cubes, which work particularly well if you’re doing the activity outdoors on a breezy day.
- Depending on your students, you may skip Steps 1–3 and have students use plain paper plates for Step 4.

#### Doing the Activity

- Pass out “tree cookies” and have your students examine the growth rings. If you don’t have an actual tree cross-section, you can draw a big one on the board. Explain that the number of rings indicates the age of the tree trunk or branch at the time that it was cut.
- Give each student either a blank sheet of paper or a white paper plate.
- Tell students to imagine that they are trees. Have them draw a cross-section of themselves, representing their age in growth rings. You might want to laminate these drawings to make them more durable.
- Have students stand about three feet apart on their own pieces of paper or plates to represent trees. Tell students that they are going to play a game called “Every Tree for Itself.” The game is a model of how trees grow. Explain to students that the colored squares represent two of the things that trees need to survive: blue represents water and yellow represents sunlight. The object of the game is for the “trees” to gather as many squares as they can. Reinforce the concept that water and sunlight are NOT the only resources that plants need to grow.
- Equally distribute the blue and yellow squares on the floor around the students so the squares are about one to two feet apart.
- Give a signal to start the first round. Have student trees reach with their branches (arms) to gather their water and sunlight. Tell students that their feet are their roots and must remain planted on their paper at all times. They are not allowed to slide their paper along the floor or step off it; they will be disqualified for doing so.
- Allow student trees to gather water and sunlight for one 30-second round. Have students count the number of squares representing each need that they gathered and record the number in their journals. Use the following questions to discuss the results of the first round:
- How many water squares and sunshine squares did each tree get?
- Did any trees get only a few water or sunshine squares?
- What might happen to a real tree that lacked one of these items? (It might grow slowly or eventually die.)
- Is there such a thing as too much water or too much sunlight? (Yes, a plant can become stressed or even die.)

- Have students stand on their papers or plates closer together in groups of three to five. Gather the colored squares and spread them around the room again. Play another round and have student trees record their results.
- Compare the results of this round with those of the first. In most cases, students will notice that each tree gathered fewer squares. Ask if they can reach any conclusions about trees that grow close to each other. (Trees close together must share or compete for the things they need. Often they don’t grow as well as trees that are more widely separated from one another.) Ask if any trees suffered because they couldn’t get enough squares to meet their needs. (You can allow trees to fall down or look tired and droopy if they haven’t received enough of each type of square.) Revisit the Essential Questions for Level B, asking such questions as: How might the time of year affect the sunshine or water a tree gets? Do you think trees grow more in the winter or the summer? What makes you say so?

Remember to visit the Enrich tab for recommended children’s books that support the science concepts covered in this activity.