What Is That “Worm” on My Pellet?

Activity: “Close the Cafeteria” (Sterilization Stops the Chain)

This activity teaches why sterilization matters, without suggesting any classroom pellet problems. It frames the idea correctly: in nature pellets can be used by recyclers; in classrooms we sterilize so the pellet stays evidence.

Grade Level

Grades 3, 8 (easy to simplify for 2, 3 or extend for 6, 8)

Time

15, 25 minutes

Objective

Students model how sterilization stops decomposition/consumer pathways, keeping a pellet as evidence instead of becoming habitat.

Prep: Make Simple Cards

Write one term per card (you can add simple drawings if you want):

• Owl (predator)
• Mouse/Vole/Shrew (prey)
• Pellet (fur + bones)
• Recyclers (label as “tiny consumers/decomposers”: moth larvae, beetles, fungi, bacteria)
• Sterilization (OBDK step)
• Classroom (lab)
• Optional cards: Habitat, Evidence, Food Web, Time

2. Ask: “In nature, what happens when organic material sits around?”
Students add: Recyclers → break down fur/feathers
Now your chain looks like:
Owl → Prey → Pellet → Recyclers

3. Introduce the Sterilization card and place it between pellet and recyclers:
Owl → Prey → Pellet → Sterilization → Classroom
Say (teacher-safe, confidence-building):
“Sterilization closes the cafeteria. The pellet stays evidence for learning.”

4. Discussion prompts (quick but powerful):

• What does sterilization remove from the system?
• What remains? (bones + evidence)
• Why is that important in a classroom?

Optional Extension: CER Mini-Write (5 minutes)

Claim: Sterilization changes what happens to a pellet over time.
Evidence: Pellets contain fur/feathers; recyclers can use those materials; sterilization stops the chain.
Reasoning: If the “recycler pathway” is stopped, the pellet stays stable for study.

Exit Ticket (One Sentence)
“Sterilization ‘closes the cafeteria’ because __________.”

Teacher-Friendly Script (If Students Ask)

“Sometimes in nature, untreated pellets can attract tiny recyclers because pellets contain fur and feathers. Our classroom pellets are sterilized, which stops that food chain, so we can focus on the evidence inside.”