Grades 6–8 · Soil & schoolyard
Underfoot: what's living in our schoolyard soil?
A single soil sample turns the ground under students' feet into a real biodiversity investigation.
Students compare two schoolyard soil spots — like a garden bed and a well-worn lawn path — by building one composite soil sample from each area over time, then argue from eDNA evidence about which spot supports more life underground.
Grade band
Grades 6–8
Time required
4 class periods
Class size
20–32 students, one kit
Sample type
Soil, one vial
Standards and outcomes
- MS-LS2-1 — Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations
- MS-LS2-4 — Construct an argument supported by empirical evidence for how changes to physical or biological components of an ecosystem affect populations
- MS-ESS3-3 — Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment
- Science & Engineering Practices — planning investigations, analyzing and interpreting data, constructing explanations, engaging in argument from evidence
How one kit serves a whole class
The $200 Classroom Starter Kit holds ONE soil collection vial and can target up to FIVE species or species groups. Rather than one shovelful representing an entire plot, crews collect several small soil cores from spread-out points in one area and combine them into a single composite sample. Results return in 7–10 days in the class Field Journal, showing detections and relative signal strength for each target.
Choose one
Research tracks
Track A — The Decomposer Crew
Who breaks down dead leaves and food scraps in our soil?
Driving question. Which decomposers are actively working in our healthiest-looking soil spot?
Species to pick. Five decomposer categories common in most regions: an earthworm species, a soil-dwelling beetle, a fungal decomposer group, a soil nematode category, and a mycorrhizal fungus group.
What students take away. Students connect the number of decomposers detected to how rich and crumbly the soil looks and feels.
Track B — Stomped or Safe
How foot traffic changes what lives in the soil
Driving question. Does a well-worn path have fewer soil organisms than an undisturbed garden bed?
Species to pick. Five species or groups sensitive versus tolerant of compaction (a burrowing invertebrate that needs loose soil, paired with a hardy microbe or invertebrate group known to survive compacted ground).
What students take away. Students use presence and absence across two spots as evidence for how foot traffic reshapes soil life.
Track C — Plant Partners Underground
Relationships between plant roots and soil organisms
Driving question. Are the organisms that help plants grow actually present in our garden soil?
Species to pick. Five root-zone species or groups: a mycorrhizal fungus, a nitrogen-fixing bacteria group, a beneficial soil nematode, an earthworm species, and a root-feeding pest to compare against.
What students take away. Students connect plant health in the garden bed to which helpful (or harmful) organisms actually turn up.
The lesson sequence
Step by step, with teacher notes
- 01
Picking our five and our two spots
45 minutesStudents choose two schoolyard spots to compare (like a garden bed and a mowed lawn) and pitch which five species or groups the class should target. Each pick needs a reason connected to soil health, not a guess, and everyone records a prediction for each spot before sampling.
Teacher notes
- Say: "We only get five species slots on this kit — tell the class why your pick deserves one."
- Show students photos or a simple map of the two candidate spots so the comparison feels concrete.
- Require each pitch to end with a prediction: 'I predict we'll find more of this in [spot] because...' — collect these before the vote.
- Vote as a class and write the final five species where everyone can see them for the rest of the unit.
- Catch any picks that go beyond the kit's five-species limit and redirect the conversation before voting.
Materials
- Photos or map of the two candidate soil spots
- Poster or board for voting
- Prediction sheet
- Simple soil organism reference sheet
Student prompts
- What does this organism need to survive in soil — moisture, loose ground, decaying matter?
- Which of our two spots seems more likely to have it, and why?
- What would finding this organism in one spot but not the other actually tell us?
- How is your reasoning different from a classmate who picked a different species?
- 02
Digging up one composite sample
45–55 minutesThe whole class builds exactly one composite soil sample from the chosen spot. Crews collect small soil cores from several points across the area and combine them into the single vial. Gloves are required before any tool or soil is touched, and hands stay away from faces throughout.
Teacher notes
- Say before any trowel comes out: "Gloves on first. If a glove touches your face or the inside of the vial cap, swap it for a new one."
- Mark three or four collection points across the plot ahead of time with flags so the sample truly represents the whole area, not just one corner.
- Rotate jobs — digging, measuring, note-taking, sealing — so every student has a real task.
- Demonstrate mixing the soil cores together gently before the sealing crew packs and labels the composite vial.
- Have a backup day ready; soil that's frozen or soaked from heavy rain won't give a representative sample.
Materials
- 1 soil eDNA collection vial and prepaid mailer
- Nitrile gloves (one pair per student, minimum)
- Small trowels or soil corers
- 3–4 sample cups or bags
- Clipboard with field data sheet
Student prompts
- Digging crew — collect small soil cores from three or four spread-out points in the plot.
- Note-taking crew — record depth of each core, soil moisture, and anything visible in the soil.
- Measuring crew — check soil moisture and note ground cover (grass, mulch, bare dirt).
- Sealing crew — combine the cores gently, seal the vial, and prepare the mailer.
- 03
What happens to our soil sample in the lab
40–45 minutes, during the 7–10 day waitWhile the sample is processed, students learn the basic steps the lab follows: pulling DNA out of the soil, copying it, reading it, and matching it against known species. Students also discuss why a strong signal for an organism doesn't mean a huge population.
Teacher notes
- Treat the wait as a full lesson, not downtime — this is a good place to slow down on the molecular concepts.
- Sketch the pipeline on the board: pull DNA out of soil → copy it → read it → match against known species.
- Say: "A strong signal might mean lots of small organisms, or fewer large ones, or organisms very close to where we dug — it's not an exact count."
- Introduce 'false negative' and connect it to why the class collected soil from several points instead of just one hole.
- Show a sample Field Journal report if time allows, so students know what to expect on reveal day.
Materials
- Simple diagram of the soil DNA lab process
- Sample Field Journal report
- Vocabulary handout (DNA, sample, detection, signal)
Student prompts
- Why might DNA break down faster in warm, sunny soil than in cool, shaded soil?
- What's the difference between 'this organism was detected' and 'there are a lot of them here'?
- How did collecting from several spots help reduce the chance of missing an organism that's really there?
- 04
Reveal day and defending our claim
45 minutesThe class Field Journal results are revealed together. Students compare predictions to actual detections, discuss any surprises, and write a short claim-evidence-reasoning paragraph about which spot supports more soil life and why.
Teacher notes
- Reveal results live and give students a moment to react before moving into analysis.
- Have students sort their predictions into 'matched' and 'did not match' on the board.
- Ask: "What's the most surprising result here, and what could explain it?"
- Require every claim to cite an actual detection or signal value from the Field Journal, not a vague impression.
- Close by asking each student to write one new question this data raised for a future soil investigation.
Materials
- Class Field Journal report (projected)
- Claim-evidence-reasoning worksheet
- Sticky notes for sorting predictions
Student prompts
- Claim — which of our two spots seems to support more soil life, based on the evidence?
- Evidence — which species were detected, and how strong was each signal?
- Reasoning — connect what each organism needs to survive to what we did or didn't find.
Student handout
For every student
Thinking prompts
- Write your prediction for each of the five target species in each of the two spots.
- Explain why your crew picked these five species or groups for this comparison.
- Describe, in order, exactly how your crew collected and combined the soil sample.
- In your own words, explain why the sample needs to be collected and shipped quickly.
- Predict one organism you think will NOT be detected, and explain your reasoning.
- After the reveal, list which predictions were correct and which were not.
- Describe one thing you would change if your class ran this comparison again.
Data sheet
- Date and time of collection:
- Plot name or description (e.g., garden bed vs. lawn path):
- Soil moisture and ground cover:
- Weather conditions that day:
- Number of soil cores taken and their locations:
- Anything visible in the soil during digging (roots, insects, worms):
- Target species list with pre-reveal predictions:
Discussion questions
- Why is combining several soil cores better than digging just one hole?
- What does 'relative signal' mean, and why isn't it the same as counting organisms?
- How might recent weather or watering have changed what we found?
- What would you do differently if we tested these same two spots again next season?
Field checklist
- Gloves on before anyone touches soil or tools.
- Soil cores taken from at least three spread-out points in the plot.
- Depth, moisture, and ground cover recorded on the data sheet.
- Cores mixed gently and sealed without touching the inside of the vial or cap.
- Sample labeled clearly with plot name and date.
- Any visible organisms in the soil written down on the data sheet.
Analysis
Claim, Evidence, Reasoning: which spot supports more soil life?
- 1.Claim — write one sentence saying which of the two spots better supports your target species.
- 2.Evidence — list the specific detections and signal strengths, plus conditions recorded (moisture, cover, weather).
- 3.Reasoning — explain, using what each organism needs to live, why the evidence supports your claim.
- 4.Counter-evidence — name one result that doesn't fit your claim neatly, and explain how you handle it.
- 5.Revise — describe one change you'd make to strengthen this investigation next time.
Assessment
20-point rubric
Species picks and predictions
5 ptsEach of the five chosen species or groups has a clear, soil-health-based justification.
Field procedure and safety
5 ptsGloves, multiple sampling points, and accurate data recording are all followed correctly.
Reading the results
5 ptsDetections and relative signal strengths from the Field Journal are described accurately.
Claim, evidence, reasoning
5 ptsThe written claim is clearly supported by specific evidence and sound reasoning about soil organisms' needs.
Go further
Extensions
- Run the same comparison again in a different season and see whether the results change.
- Have students design a next-round species list based on this round's most surprising result.
- Overlay simple watering or mowing schedule data to help explain the detection patterns.
- Invite a school garden volunteer or local extension agent to review the class's conclusions.
For the teacher
Answer key and misconceptions
- Expected: most classes detect two or three of their five target species per spot; zero detections points to a timing or depth issue, not a broken method — discuss this openly.
- Common misconception: 'we didn't detect it, so it's definitely not there.' Correct framing: a detection reflects what DNA was present in that soil sample, not a guarantee of absence.
- Common misconception: 'more signal means more organisms.' Correct framing: signal strength reflects how much DNA was present in the sample, which depends on organism size, density, and location relative to the cores taken.
- Expected: students should connect faster DNA breakdown in warm, sunny soil to why the sample must be shipped the same day it's collected.
- Common misconception: contamination only matters in the lab. Correct framing: gloves and clean tools during digging are student-side steps that directly protect the accuracy of lab results.