FOCUS: Wood, leaves, bark, roots, flowers, and fruits: disassembled, these various parts don’t begin to convey the majesty of a mighty tree in full summer foliage. However, each part of the tree serves an important function that contributes to its survival. Roots reach into the soil for water and nutrients, wood provides strength for the trunk, branches hold the crown of leaves up to the sunlight. Like other living organisms, trees grow, reproduce, and die, but they are more to us than just tall woody plants: they are neighbors that grow and change with us through the years.
Objective: To begin to explore and ask questions about trees.
Hold up a small cardboard box and tell the students that you’ve discovered a beautiful object that can turn sunlight into sugar, pump gallons of water a day, purify air, move and split rocks, change color with the season, and provide shelter and food to all sorts of animals. What do they think it is? Open the box and present the small sapling hidden inside.
Materials: cardboard box, small sapling.
Objective: To explore the variety of trees in a nearby area.
With children in groups of six to eight, take a walking tour of nearby trees looking for:
- A sapling tree – can you reach your hand around it? Feel the bark.
- A really big tree – can you reach your arms around it? Feel the bark. Can you reach the lowest branch?
- Exposed tree roots.
- Different textures of bark.
- A lopsided tree. Can you tell why it is growing this way?
- Three or four different kinds of trees. How can you tell these are different species?
Take a moment to have children act out the posture of the different trees, the angle at which they hold their branches, and the movement and sounds they make in the wind. Afterward, ask children what questions they have about the trees they visited. Discuss which of these questions could be answered by an investigation.
Materials: optional: tree identification guides, Trees Aid to Identification.
TOUCH A TREE
Objective: To examine a tree carefully using only the sense of touch.
Gather the whole group together at a central spot outside. Choose one volunteer and demonstrate how to carefully lead a partner whose eyes are closed to a tree, gently holding his bent arm and describing the landscape across which the two of you are moving. Now pair up children and explain that children will take turns being leader or explorer. In each pair, the sighted partner will lead the partner whose eyes are closed to a nearby tree to examine and then guide the exploration with questions like:
Can you wrap your arms around the tree? How far up is the lowest branch of the tree? How many branches can you reach? Is the bark rough or smooth? What’s unusual about this tree?
Can you feel any leaves on this tree? Describe them.
Afterward, leaders escort their partners back to the central spot, gently turn them around a few times, and then ask them to open their eyes. Can the explorer find his/her tree? What characteristics were key to identification? Change roles and repeat.
UPPER GRADES CHALLENGE: MEASURING TREES (Grades 5-6)
Objective: To measure girth and estimate tree height and age.
Have students work in small groups, each with an adult leader. Have each group gather by a tree on the school grounds or nearby. Use the Measuring Trees Worksheet as a guide.
To estimate the height of a tree, have someone of known height stand next to the tree. Have the other children walk away from the tree until they can see the whole tree from top to bottom. Estimate how many people of the same height could fit if stacked standing one atop the other from the base to the top of the tree. It helps to hold up a ruler, marking off the height of the person from that distance, and then count how many of that measurement fit from ground to treetop. Multiply this number by the person’s height to get the approximate height of your tree.
To measure the trunk’s radius, begin by making a chalk mark at a height of 4 ½ feet above the ground. Explain that foresters measure a tree’s diameter at breast height, or “DBH.” Next, measure around the trunk at this height, using a tape measure. This is the tree’s circumference. To find the diameter, divide the circumference by 3.14 (pi). Then divide the diameter by 2 to find the radius.
The next step is to estimate the rate of growth of your tree. Based on the size and fullness of the crown, the color of the leaves, signs of rotten or dead wood, and crowding by nearby trees, have children consider whether the tree has been able to grow at a fast rate (1 inch in 3 years), a slow rate (1 inch in 10 years), or an average rate (1 inch in 7 years.) To find the tree’s approximate age, multiply the radius by the rate of growth they chose (3, 7, or 10). About how old is your tree? What might help your tree grow faster or be healthier? Can a slow-growing tree be healthy?
MEASURING TREES: WORKSHEET
__________A. Height of tree: estimate by deciding how many people of known height could stand on top of each other to reach the top of the tree
__________B. Circumference: measure around tree at chest height (4½ feet)
__________C. Diameter: divide circumference by 3.14 (pi)
__________D. Radius: divide diameter by 2.
__________E. Growth rate: How healthy and full does it look? Has it grown:
Slowly = 10 years to grow an inch,
Average = 7 years to grow an inch,
Fast = 3 years to grow an inch?
__________F. Age of tree: multiply radius X growth rate.
Materials: Measuring Trees worksheet; clipboards and pencils, tape measures, rulers; optional: calculators.
Objective: To observe and record information about a living tree out of doors.
Have each pair or small group of children pick out a tree (one in the open where they can see the top) for the next two activities. Using the Draw a Tree sheets, have them draw a picture of their whole tree, a leaf from the tree, and the tree’s seed or fruit, if they find one. Have them make a rubbing of a leaf and of the bark.
Materials: Draw a Tree sheets, pencils, crayons, clipboards.
INTERVIEW A TREE
Objective: To make and record observations about a particular tree.
Pair up children, and give each team an interview form and pencil. Send two pairs out together to choose a tree and answer the questions. When finished, have pairs compare findings. Afterward, gather as a whole group and ask each team to share its favorite interview question. Discuss whether any of these are questions that could be answered with an investigation.
INTERVIEW A TREE
Hello, Tree. Thank you for agreeing to this interview. We’re delighted to have this chance to get to know you better.
Are you a young tree, grown up, or very old?
What did this area look like when you were just a seedling?
How many children would it take to hug you all the way around?
Please describe your leaves.
Are you taller or shorter than any neighboring trees?
What’s the most challenging thing about growing in this spot?
What animals might eat your seeds or fruits or make a home in your branches?
What is living or growing in your shade?
What is special about you?
Now record one additional question you’d like to ask your tree:
Materials: Interview a Tree scripts, pencils, clipboards.
PUPPET SHOW “Tree-mendous Trees”
Objective: To learn some of the parts that make up a tree and the functions each serves.
Perform the puppet show or have the children perform it for each other. Afterward, review key vocabulary and parts of a tree by having the children stand up and imagine being a tree. Stretch their roots (toes) down into the soil to pull up water and nutrients. Reach up to the sky with their branches (arms). Spread their leaves (hands) wide to capture some sunlight.
Materials: puppets, script, props, stage.
TREE TRUNK ACTION
Objective: to model the different layers in a tree’s trunk and learn how they function.
Hold up a large tree cookie or the Tree Slice diagram and ask children what they notice about the inside of a tree’s trunk. Explain to the children that they will be helping you make a model of the layers of wood inside a tree’s trunk. As you select students for each role, give them the corresponding What’s Inside Label to wear around their necks.
Select one student to represent the wood at the very center, or heart, of the tree (heartwood). Explain that to represent this part of the tree they will flex their muscles and chant, “I’m big and strong,” over and over. Next, have three students be the layer of wood surrounding the heartwood, which is full of sap (sapwood). Explain that they transport sap both up and down in the tree. Have these students hold hands, then together raise and lower their hands while chanting, “Sap going up, sap going down.” Then add the outer layer surrounding and protecting the tree (bark). Select several students to join hands in a circle around the sapwood. Explain that they have two roles: their outer bark protects the tree and their inner bark helps transport food from the leaves throughout the tree. To represent their protector role, while raising their arms above their heads, have them bark and growl, then when lowering their hands chant “Food going down.” Lastly, add the microscopic layer that helps the tree to get wider each year (cambium). Place one person between the bark and sapwood and have them circle around inside the trunk chanting, “I make new wood, I make new bark.” The cambium adds a new ring of wood and a new ring of bark to the trunk of the tree each year. Starting from the inside layer and working out, have each group illustrate their function by chanting and making their accompanying motions. Then, since all these functions happen at the same time, have everyone perform at the same time.
Materials: Tree Slice diagram, or large tree cookie; What’s Inside Labels representing the layers of the tree, heartwood (1), sapwood (3-6), bark (6-12), cambium (1), with strings to wear around the neck.
READING THE RINGS
Objective: To observe the parts of a trunk and see how wood records the life of the tree.
With children in small groups, give each child a tree slice (thin section of a tree trunk or branch) to examine using a magnifying lens. Some things to observe include: rings, pith, heartwood, sapwood, bark. Use the Tree Slice diagram as a guide. Point out the line between the wood and the bark where the cambium is located, and discuss how a tree grows by adding new layers of wood and bark. What part of the wood is the oldest? Can you find places in the rings that show faster growth? (Farther apart.) Slower growth? (Closer together.) What might have caused these differences in growth? (Shading, amount of rainfall, temperature, etc.) Count the rings to estimate the age of your tree. Is it older or younger than you?
Encourage children to compare their tree slice with others in the collection. What differences do they notice between various slices?
Materials: tree slices, at least one per child; Tree Slice diagram; magnifying lenses.
A STEP BEYOND
General Sherman: With the students’ help, measure a line of thirty-two feet, roughly the diameter of General Sherman, the famous Giant Sequoia with the largest trunk. Place a student at each end of this line and one in the middle. Now mark another thirty-two foot line intersecting the first at 90º, again using students as markers. Have the rest of the children form the rest of the circle, a circumference of about 100 feet. Now have them imagine a tree trunk as big as the space in the middle of the circle. This is about how big around General Sherman is at ground level!
Tree, Tree, Poetry: Have small groups of children work together to write a poem about a tree they are visiting. Give each child a spot from which to view the tree – next to the tree trunk, at arm’s length from the tree, sitting under the tree branches, from a distance so the whole tree can be seen. Have children contribute three to five words each, describing the tree from their different perspectives. Now have each team of children work together to use all their words to craft a poem about their tree. Afterward, have teams share their poems and introduce their tree to the others. Be sure to take a photograph of the poets near their trees for a display of photos and poems.