Key Concepts: photosynthesis, producers, herbivores, omnivores, carnivores, apex predators, decomposers
All living things need energy, and this energy flows through the ecosystem in predictable patterns. Students learn how the sun’s energy moves through producers (plants), consumers (animals), and decomposers (organisms that break things down). They discover that producers are the foundation of all food chains, and without them, there is no energy for anything else.
The lesson also introduces food webs — more complex diagrams showing that ecosystems aren’t simple straight lines but networks of interactions. Students understand why removing even one species can disrupt many others.
Real-Life Examples:
- School lunch: Bread comes from wheat (a plant), cheese comes from cows that eat grass, and vegetables rely on sunlight and soil nutrients.
- Rainforest: Plants → insects → frogs → snakes → hawks → decomposers
- Ocean: Phytoplankton → krill → penguins → seals → sharks → decomposers
- Composting at home: Leftover fruits and vegetables become nutrient-rich soil through decomposer activity.
Students analyze what happens if a part of a food chain becomes weak — for example, if a disease reduces the plant population, herbivores may starve and predators lose their food supply.
