Raven has drawn two boxes on the whiteboard. "Two designs," she says. "Then we pick, or we combine."
Rocket taps the first. "Foil box. Shiny walls on three sides bounce window light onto the dark side of the sprouts."
"And the second?" Raven asks. "What do you notice about how the sprouts lean?"
"Toward the glass," Rocket says. "So design two is a turntable. We turn the jar a half turn every morning."
Nova hovers between the drawings. "What does each design do about water?" she asks.
Rocket groans. "Nothing. Yet." He adds a small cup and a note to both sketches: check the paper towel is damp daily.
Last week's sprouts bent toward the window. That is positive phototropism: the tip senses light and the stem bends toward it.
A stem that leans one way is reaching for light that comes from one side. Giving the sprout light from more sides may keep it upright.
Photosynthesis needs sunlight, carbon dioxide and water. Window light brings the first. Air brings the second. The damp paper towel brings the third.
Environmental factors include light, water and space. Your station can change the first two. Crowding the jar would hurt the third.
Each of these facts rules some ideas out and points toward others. That is what engineers mean by science limiting the solutions.
Engineers often compare several solutions. Sometimes parts of different solutions can be combined into a solution better than any of them alone.
Design A is the foil box: a cardboard box with one side cut away and lined with foil. The jar sits inside, open side toward the window.
Design B is the turntable: the jar sits on a plate that is turned a half turn each morning. A strip of tape marks the turn.
Both keep the paper towel damp. Both leave the plain control jar exactly as it is, in its usual spot.
You may build A, B or a combination. Whatever you build, it is tested against the plain jar, not against a guess.
| Design | How it uses the science | Criterion it targets most | Possible problem |
|---|---|---|---|
| A: foil box | Bounces window light onto the shaded side | Upright stems | Box could shade the jar if placed wrong |
| B: turntable | Gives each side a turn facing the window | Upright stems | Easy to forget a turn |
| A and B combined | Both | Upright stems and height | More to do each day |
| Statement | True or false? |
|---|---|
| Parts of different designs can sometimes be combined into a better one. | ? |
| The control jar should be changed along with the station. | ? |
| Window light, air and a damp towel supply the three inputs of photosynthesis. | ? |
| Crowding more jars into the box improves the space factor. | ? |
Clear thinking. Tomorrow is Windowsill Lab: you build the station, set the control and take the first measurements.