Full-grown trees may be awe-inspiring, but fourth graders in St. Paul, MN, place their bets on the promise inside the seeds.
"As part of our 'trees are the key' program, we ask all students to collect and bring in seeds from trees growing in our area or found in supermarket fruits," says Environmental Educator Lynn Baerthel. Then the detective work begins.
Once Lynn's young scientists collect, display, and compare seeds, they research where the trees typically grow, then theorize what conditions will help bring them to life. For instance, they predicted that oranges and lemons, denizens of warm climates, might grow nicely under lights in the classroom. "When we discussed the local tree seeds we'd found in the fall, I had students imagine what would happen if they sprouted just before our cold winter," says Lynn. Prompted by a rough grasp of dormancy, her problem solvers tested their theories by chilling some seeds for several months to mimic winter conditions and leaving others in a warm spot before trying to grow them. "Of the warm crops, orange and lemon seeds grew nicely, but mangoes didn't come through," says Lynn. She adds that acorns and Ohio buckeye, maple, and honey locust seeds germinated fairly well, but the latter's hard seed coat required scarring with sandpaper. "When we did have 'failures,' we brainstormed what might have caused them -- our setup, pests and diseases, and so on -- and imagined how natural conditions might help or hinder seed germination," says Lynn.
With images of a schoolyard full of "treelings," the class obtained clear plastic tubes 1/2 inch to 2 inches in diameter and 6 to 12 inches long in which to plant seeds. "This type of setup, filled with soil mix, nicely protects roots, which can quickly get long," says Lynn. Since each student had quite a few seeds to work with, the class was able to experiment with different variables, light height, amount of fertilizer, and so on. "What excitement when the leaves emerged and students got to compare and identify their treasures," says Lynn. Six weeks after planting (late April), students moved their 8-inch-tall trees into 6-inch soil-filled pots, to create an outdoor nursery, then planted them in the ground by the end of the school year.
While their young charges grew, Lynn's students adopted and kept tabs on mature trees nearby, maintaining journals rife with tree photos, drawings, and pressed leaves. They also observed trees and shrubs for evidence of seed dispersal mechanisms, categorizing their finds as spinners, drifters, grabbers, floaters, and feeders (those digested and excreted by animals.) After examining the rings on trunk slices (or "cookies") kids wrote life stories from the tree's perspective.
"The fact that our tree studies have been fairly inquiry-oriented has boosted students' confidence in their ability to figure things out," says Lynn. "It has also been fascinating to see them begin taking another point of view (that of the trees!) and, in doing so, becoming more protective stewards."