Ecology

What this covers

• Building and reading food chains, food webs and energy pyramids, including why only about 10% of energy passes to the next trophic level
• Naming and comparing symbiotic relationships: mutualism, commensalism, parasitism, plus predation and competition
• Tracing the carbon, water and nitrogen cycles through living and nonliving parts of an ecosystem
• Explaining limiting factors, carrying capacity and how predator and prey populations affect each other over time
• Distinguishing biotic from abiotic factors and organising levels from organism to population, community, ecosystem and biome
• Predicting effects of disturbance — invasive species, habitat loss, pollution — and describing ecological succession after a fire or flood

Where learners get stuck

Thinking arrows in a food web show 'who eats whom' rather than the direction energy flows

The arrow points from the eaten organism to the eater, which feels backwards when you read the diagram as a sentence. Students draw arrows from the hawk to the mouse and then misread the whole web.

Believing plants get their mass and food from the soil

Watering and fertilising plants makes soil feel like the food source. The idea that most of a tree's mass comes from carbon dioxide in the air contradicts everyday experience, so it needs to be worked through with the photosynthesis equation.

Assuming removing a predator is good for the ecosystem because prey survive

Predators are framed as harmful in stories and cartoons. Students need to reason through a specific case — deer without wolves overgrazing plants — to see that populations without limiting factors overshoot carrying capacity.

What a session looks like

A session is a spoken back-and-forth. Evelyn might start with a described ecosystem and ask the learner to sort the organisms into producers, consumers and decomposers, then remove one and ask what happens next and why. Diagrams like food webs and energy pyramids are talked through step by step, with the learner saying which way the arrows point and how much energy reaches the top. When an answer is partly right, Evelyn asks a follow-up rather than giving the answer, and returns to the same idea later in a different ecosystem to check it stuck.

Helpful to know first

• Knows that living things need energy, water and air to survive
• Can read a simple diagram with arrows and labels
• Comfortable with percentages and simple fractions for energy transfer
• Basic idea that plants make their own food using sunlight

Questions

What ecology topics are covered in 6th, 7th and 8th grade science?

Most state standards cover ecosystem levels and biotic/abiotic factors, food webs and energy flow, symbiotic relationships, matter cycles including carbon and water, population dynamics and carrying capacity, and human impacts such as invasive species and habitat loss. Sessions can follow whichever order your child's class is using.

How do I explain the 10% rule to my child?

Most energy at each level is used for movement, growth and body heat, or lost as waste, so only a small fraction is stored in the organism's body and available to whatever eats it. Evelyn works through it numerically — 10,000 units in the grass, 1,000 in the grasshoppers, 100 in the frogs — so the shrinking pyramid shape makes sense.

My child mixes up mutualism, commensalism and parasitism. Can this help?

Yes. Evelyn drills these with concrete pairs — clownfish and anemone, barnacle and whale, tick and dog — and asks the learner to state what each organism gains or loses. The sorting practice repeats across sessions until the labels come quickly.

Does this cover science fair or lab report work on ecosystems?

Evelyn can talk through designing an ecology investigation, choosing variables, and interpreting population data or field observations. It works by voice, so it discusses and questions the plan rather than writing the report for the student.