Living Root Garden School • Soil & the Underground • Name: ______________________
🔍 The Case
The case of the invisible internet — plants are trading with something underground you cannot see. Find the partners.
Mycorrhiza means fungus-root. Mycorrhizal fungi move into or cozy up around plant roots and form a win-win partnership: the plant pays them in sugar, and the fungi deliver water and nutrients — especially phosphorus, which barely moves in soil on its own.
The fungi send out microscopic threads called hyphae, thinner than even the finest root hairs, that squeeze into tiny soil pores roots cannot enter. That is how they reach past the nutrient depletion zone — the thin shell of soil around roots where phosphorus gets used up fast.
Look for the partners where fungi fruit: after rain, on old logs, in mulch, and in shady damp corners. The mushrooms you see are just the fruit — the real fungus is the thread network underground, trading with the roots above it.
Rule out the loners: plants in the Brassica family — broccoli, cabbage, cauliflower, kale, Brussels sprouts, turnips — do not form mycorrhizal friendships. They said, we will do it ourselves. And heavy phosphorus fertilizer makes plants ditch the fungi too, because why pay for a delivery service when the fridge is already full?
Ask: Which plants in your yard do you think have fungal partners underground, and which one does not? Write your guess before you hunt.
Try: Find fungi growing in the yard, sketch each one where it grows, and note what plant or tree it might be trading with. Look only, never taste.
Stretch (Teens & Growers ready for more): Diagram the trade deal with real terms — sugars down, phosphorus and water up — and draw what happens if the fungus goes missing: the plant's reach shrinks back to its own roots.
Tell: Fill in the log below — date, each fungus you found, what plant it was growing near — then finish this sentence in words or a labeled drawing: “The fungus was trading with ___ because ___.”
Date
What I saw
What surprised me
Date: ____/____/____
Date: ____/____/____
Date: ____/____/____
Date: ____/____/____
🛠️ Build It
Draw the trade deal: a plant handing sugars down, a fungus handing water and phosphorus up — label who gives what.
🗣️ Be the Teacher
Show someone your trade drawing and explain the deal — sugars down, phosphorus and water up — in your own words, no reading off the packet.
🏅 I can…
☐ I can explain the sugar-for-phosphorus trade.
Portfolio check
☐ Guide read
☐ Case solved
☐ Ask, Try, Tell done
☐ Build It filed: Fungus sketches (+ trade diagram for teens)
☐ Taught someone
☐ Badge earned: I can explain the sugar-for-phosphorus trade.
Living Root Garden School • livingrootgarden.com/homeschool/ • Free — print as many copies as you like. File this sheet with your portfolio log. Sprouts do the Read, the Case, and Build It; Growers try the Ask, Try, Tell stretch when ready; Teens do the whole packet — including teaching it back.