Preview · the opening missionRead this to the class:
A storm brought down an old oak in a city park. The trunk alone filled a truck. A Grade 7 student looked at the stump and asked: "Where did all that wood come from? There's no giant hole in the ground." Four hundred years ago, a scientist in Belgium asked the same question, and he weighed everything. Your team's job: use his numbers and five modern clues to decide what a tree is really made of.
Teams of three, rotating jobs: Reader (reads cards aloud), Calculator (does the numbers), Recorder (writes the claim).
Look inside the PDF
Sample pages, stamped “preview”. The download is the clean, full lesson.
In the full lesson PDF
8 printable pages
- Predict (5–10 min)
- Hunt (20 min)
- Reveal (10–15 min)
- Act (10 min)
- Background for the teacher
- Assessment
- Student sheet
- Worksheet: Evidence cards
- Worksheet: Label it
- Worksheet: Try it at home
On the student sheet
- My prediction
- Card A numbers
- Opinion line counts
- Our claim, with the two strongest cards
- Exit ticket
- Evidence cards
- Label it
- Try it at home
US Letter, prints cleanly in black and white. The student sheet is on its own page, ready to photocopy.
Free with an account (any 3 lessons), or US$19 for all 3 lessons in this unit.
What students show by the end
- Uses van Helmont's data
- Explains where mass comes from
- Uses the equation
From the lesson’s rubric, which scores each one as not yet, getting there or got it.
Questions teachers ask
How long does “Where does a tree's mass come from?” take?
50–60 min. Group size: teams of 3.
How much prep does it need?
10 minutes: print the Evidence cards, one set per team, cut apart. Clear a line across the room, about 6 m (20 ft), and put a sign at each end: MOSTLY SOIL and MOSTLY AIR, with WATER in the middle.
What materials do I need?
None. No materials needed: just the printed sheets.
Which curriculum standards does it cover?
NGSS (US): MS-LS1-6. It also matches England National Curriculum, Key Stage 3 and Cambridge Lower Secondary Science, Stages 8 and 9 (not endorsed by Cambridge).
What’s in the lesson PDF?
A teacher guide that walks you through predict, hunt, reveal, act, background for the teacher and assessment, then a student sheet (“My prediction”; “Card A numbers”; “Opinion line counts”; “Our claim, with the two strongest cards”; “Exit ticket”; “Evidence cards”; “Label it” and “Try it at home”) on its own page, ready to photocopy. It’s US Letter and prints cleanly in black and white.
Can I try it for free?
Yes. A free account includes any 3 full lessons of your choice, and this can be one of them. After that, this unit is US$19 for all 3 lessons, yours to keep, or every lesson is US$199 a year.