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Ecosystems | Lesson 1 - Unit Pretest and Key Features of Ecosystems

Lesson 1: Unit Pretest and Key Features of Ecosystems

Students take the pretest, share their ideas about where carbon is located in ecosystems, identify which carbon is organic versus inorganic, and identify the type of organisms (producers, herbivores, carnivores, and decomposers) that exist in ecosystems.

Guiding Question

What are the key features of ecosystems?

Activities in this Lesson

  • Activity 1.1: Ecosystems Unit Pretest (20 min)
  • Activity 1.2: Expressing Ideas for Patterns in Ecosystems (15 min)
  • Activity 1.3: Key Features of Ecosystems (30 min)


This lesson helps students start thinking about all of the unit objectives, but does not focus on their mastery on of any of them.

NGSS Performance Expectations

This lesson helps students start thinking about all of the NGSS performance expectations for this unit, but does not focus on their mastery on of any of them.

Background Information

In previous Carbon TIME units, students learned to explain macroscopic processes (plant growth, combustion, decay, etc.) in terms of atomic molecular processes. In this unit, they must connect the macroscopic and atomic molecular scales to matter cycling and energy flow at the larger ecosystem scale. This presents several challenges, discussed in the sections on goals and learning progressions in the introduction. Here are some questions to think about as you read your students’ pretest responses and listen to their ideas:

  • Are they distinguishing between individual plants and animals and populations or trophic levels? Students will need to learn that food chains and food webs tell about relationships between populations and flows of matter and energy, not just “who eats who.”
  • Are they distinguishing matter from energy? Matter and energy move together through food chains and food webs, so students can confuse organic matter with the chemical energy in organic matter and still answer a lot of questions correctly, but matter and energy “go their separate ways” at the beginning and end of food chains and food webs:
    • Producers get matter ONLY from CO2, water, and minerals and energy ONLY from sunlight.
    • When organisms use organic matter for cellular respiration, ALL the matter goes back into CO2, water, and minerals, while ALL the energy leaves the ecosystem as heat (which is ultimately radiated out into space). So, matter cycles and energy flows through ecosystems.
  • Are they connecting scales? Students will need to apply what they learned about transformations of matter and energy in individual organisms to ecosystem-scale processes—to see how matter cycling and energy flow in ecosystems result from the atomic-molecular processes of photosynthesis, biosynthesis, digestion, and cellular respiration. Many students find this a hard connection to make. This lesson will help students begin thinking about these ideas and will give you a chance to see where your students are starting.