- Learn-by-doing activity: Through an Interactive game (Ready, Set, Rotten!) students predict decomposition times of common objects in dry and moist ecosystems.
- Data collection: Sort fungal micro-remains into species using structure and shape. Analyze fungal populations in varied soils to help explain decomposition rates.
- Aligned to NGSS MS-LS-2-3: Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.
Decomposition: It's a Dirt-y Job
Total Estimated Time: 2-3 class periods, 120 minutesDecomposers play a critical role in the matter cycle -- they are the forgotten heroes of healthy ecosystems! This investigation will draw your students into the soil, helping them conduct a scientific investigation into why decomposition times differ in dry and moist ecosystems.
Part 1: Ready, set, rotten! (Educational game on decomposition times)
How long does decomposition take?
(20-30 minutes)
- Students predict decomposition times for common (natural) objects in dry and moist ecosystems. Will they dominate as a "Putrefying Pro" or just get their hands dirty as "Decay Dabblers"? Only time will tell!
Part 2: Hidden soil heroes (Data collection and analysis)
Why is matter cycling faster in some ecosystems than others?
(30-45 minutes)
- Led by a scientist mentor, students sort fungal micro-remains from soil samples by structure (single cell or cell cluster) and shape (rounded, pointed, or elongated). Students then compare fungal abundance and richness for each soil sample, reasoning about what fungal populations can tell us about speed of matter and nutrient cycling.
Part 3: Human help or harm? (Evidence-based argument and communication)
How do human activities affect decomposition and matter cycling?
(20-30 minutes)
- Students explore what soil color can tell them about nutrient content (and matter cycling). They then examine soils from varied human sites to reason about how human activities may affect fungal populations . . . and matter cycling!