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Free scope and sequences, TEKS breakdowns, phenomenon ideas, and engagement activities for the 2024 Texas science standards.

I'm Chris Kesler, a former award-winning Texas middle school science teacher. This is the site I wish I'd had in the classroom. One hub with TEKS breakdowns, scope and sequences, phenomenon starters, engagement ideas, and resources, all aligned to the standards you actually teach.

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7th Grade TEKS Standards

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TEKS S.7.12A • Ecosystems

Diagram Trophic Levels

The Standard

"Diagram the flow of energy within trophic levels and describe how the available energy decreases in successive trophic levels in energy pyramids."

💡 What This Standard Actually Means

The Key Verb

"Diagram". Students are diagramming the flow of energy within trophic levels and describing how the available energy decreases in successive levels in energy pyramids. The new TEKS pushes the focus to trophic levels and energy pyramids specifically, instead of the broader "food chains, food webs, and energy pyramids" wording from the old standard. Kids need to understand the layered structure of an energy pyramid and the 10 percent rule that drives it. Instruction can take many forms, such as energy pyramid drawing activities, paper-folding 10-percent demonstrations, trophic level card sorts, and ecosystem case study analysis.

Energy in an ecosystem flows in one direction. It starts with the Sun, gets captured by producers (plants and algae using photosynthesis), and moves up from there through a series of trophic levels. A trophic level is just a layer in the energy pyramid based on how an organism gets its food.

The first trophic level is producers. The second is primary consumers, which are herbivores that eat producers. The third is secondary consumers, which eat primary consumers. The fourth is tertiary consumers, which eat secondary consumers. Decomposers recycle matter and energy from every level back into the system, but they're usually drawn off to the side rather than as their own numbered level. Each step up the pyramid contains less total available energy than the level below.

The reason for the decrease is the famous 10 percent rule. Roughly 10 percent of the energy at one trophic level transfers to the next. The other 90 percent gets used by the organism for life processes (moving, breathing, growing, repairing tissue, staying warm) and is mostly lost as heat to the surroundings. So if producers in an ecosystem capture 10,000 units of energy from the Sun, primary consumers get about 1,000 units, secondary consumers get about 100, and tertiary consumers get about 10. That's why energy pyramids have such a wide base and a tiny top, and why ecosystems have many more producers and herbivores than they do top predators. When students diagram this, they should show layered levels with decreasing energy at each step and arrows that flow upward (from the eaten to the eater).

💬 From Chris's Classroom

The move that worked for me on this one was arrows, arrows, arrows. I'd have kids draw a food chain on the board, then I'd walk up and ask, "Which way is the energy flowing?" Half the room would have drawn the arrows pointing from the predator to the prey, which is backward. We'd talk through why the arrow means "energy goes this way" and the energy goes into whoever's doing the eating. Then I'd have them redraw. After that, I'd give them a stack of organism cards from a Texas ecosystem and let them build a full web on butcher paper using yarn for arrows. The minute you could pull one "string" and see how the whole thing wobbled, they got why ecosystems are connected.

⚠️ Misconceptions Your Students May Have

These are some of the most common misconceptions. Knowing what to look for can help you get ahead of them.

"The arrow in a food chain points from the predator to the prey"

✓

The arrow shows the direction energy flows, which is from the organism being eaten to the organism doing the eating. So grass-to-grasshopper means energy flows from grass into the grasshopper. Students who draw it the other way are thinking "who hunts whom," but the standard is about energy, not predation. Walk them through it on one chain and the rest of the unit gets easier.

"Exactly 10 percent of the energy transfers to the next level"

✓

The 10 percent rule is an approximation, not an exact number. In real ecosystems, energy transfer between trophic levels typically ranges from about 5 to 20 percent depending on the organisms and conditions. The takeaway students need is that MOST of the energy is lost at each step (as heat, movement, and life processes), so higher trophic levels have far less energy available to them. "About 10 percent" is the safe phrasing.

"Decomposers are their own trophic level at the top of the pyramid"

✓

Decomposers don't sit at a single level because they recycle dead material from every level. A decomposer might break down a fallen leaf one day and a dead hawk the next. That's why you'll often see decomposers drawn off to the side of a food web or energy pyramid rather than stacked above the top predators. They're essential, but they don't fit the linear pyramid structure neatly.

"Plants eat dirt to get their food"

✓

Plants are producers. They make their own food from sunlight, carbon dioxide from the air, and water through photosynthesis. Soil provides water and minerals the plant needs, but the actual energy source is sunlight. Students who think plants "eat" dirt have a hard time seeing why producers sit at the base of every food chain, because they don't recognize photosynthesis as food-making.

📓 Teaching Resources for 7.12A

These resources are aligned to this standard.

Complete 5E Lesson

Diagram Trophic Levels Complete Science Lesson

The full unit for 7.12A: differentiated station labs, editable presentations, interactive notebooks (English + Spanish), student-choice projects, and assessments. Built on the 5E model.

⏱ Best for: Full unit coverage • Multiple class periods

Station Lab

Diagram Trophic Levels Station Lab

9-station hands-on lab covering food chains, food webs, energy pyramids, and producer/consumer/decomposer roles with input stations (Explore It!, Watch It!, Read It!, Research It!) and output stations (Organize It!, Illustrate It!, Write It!, Assess It!). Print and digital. English and Spanish.

🔬 Best for: Core instruction • 1-2 class periods

Student Choice Projects

Diagram Trophic Levels Student Choice Projects

Choice board with nine project options plus a "design your own" pathway. Students demonstrate their understanding of food chains, food webs, and energy pyramids through writing, building, illustrating, presenting, or digital formats.

🎓 Best for: Project-based assessment • 2-3 class periods

🌎 Phenomenon Ideas for 7.12A

Use these real-world phenomena to anchor your lesson. Show students the phenomenon first, let them wonder, then build toward Diagram Trophic Levels as the explanation.

🔎

Phenomenon 1

Wolves Change the Rivers in Yellowstone

After gray wolves were reintroduced to Yellowstone National Park in 1995, something unexpected happened. Elk populations dropped, which allowed willow and aspen trees to recover along streams. Beavers returned because they had willows to chew. The banks of rivers became more stable. Even the paths of the rivers themselves shifted. A single change at the top of the food web rippled down to plants and the physical landscape.

💬 Discussion Prompt

"If wolves only directly eat animals like elk, how could adding wolves back to Yellowstone end up affecting trees, beavers, and even the shape of rivers?"

🔎

Phenomenon 2

Why Are There So Few Eagles Compared to Grasshoppers?

In a Texas grassland, a single square mile might support millions of blades of grass, hundreds of thousands of grasshoppers, a couple thousand mice, maybe a hundred snakes, and only a few hawks or eagles. Every step up the food chain has dramatically fewer individuals than the one below. This pattern shows up in almost every ecosystem on Earth, from coral reefs to tundras.

💬 Discussion Prompt

"Why can an ecosystem support millions of producers, but only a few top predators? What is being lost at each step that limits how much life can exist higher up?"

🔎

Phenomenon 3

A Fallen Log in the Texas Woods

A big post oak dies and falls in a Texas forest. At first the log looks mostly intact. Two years later, it's crumbling. Five years later, it's mostly gone, with mushrooms growing out of the remains and the surrounding soil noticeably darker. No single animal "ate" that tree, but all of its material got recycled back into the ecosystem and new plants are growing in the soil where it lay.

💬 Discussion Prompt

"If no single animal ate that log, where did all of its material go? What role are fungi, bacteria, and other decomposers playing in returning that energy and matter back into the ecosystem?"

💡 Free Engagement Ideas for 7.12A

Yarn Food Web

Give each student or pair a card with a Texas ecosystem organism (grass, grasshopper, mouse, snake, hawk, deer, mountain lion, oak tree, decomposer mushroom). Tape the cards to a bulletin board or butcher paper. Hand out yarn and have students connect each organism to what it eats with a yarn "energy arrow" pointing from prey to predator. Once the web is built, snip one strand (e.g., remove all grasshoppers) and trace which organisms are affected. Students see how interconnected even simple ecosystems are.

Materials: Index cards with organism names or pictures, yarn, tape, butcher paper or bulletin board, scissors

Build the Energy Pyramid

Give each group 100 unit cubes (or pennies, dried beans, or sticky notes). Tell them all 100 represent the energy stored in producers. To "feed" primary consumers, they pass on only 10 cubes. Primary consumers pass on 1 cube to secondary consumers. Secondary consumers can barely feed a tertiary consumer. Students stack their cubes into a pyramid shape and label each level. The 10 percent rule becomes obvious by the time the top of the pyramid has nothing left to give.

Materials: 100 unit cubes per group (or pennies, dried beans, sticky notes), labeled level cards (Producer, Primary Consumer, Secondary Consumer, Tertiary Consumer)

Trophic Level Sorting Challenge

Prepare cards with around 20 organisms from a single ecosystem (oak tree, acorn, deer, squirrel, hawk, owl, field mouse, snake, mushroom, earthworm, soil bacteria, grasshopper, ladybug, spider, etc.). Students sort the cards into five columns: producer, primary consumer, secondary consumer, tertiary consumer, and decomposer. Some organisms (omnivores, decomposers) can spark good debates. Each group justifies their placements out loud, and the class votes on tricky ones.

Materials: Index cards with organism names or pictures, table headers labeled by trophic level

Decomposer Time-Lapse

Place a banana slice (or a piece of bread) in a clear jar with a small amount of moist soil. Loosely cover the jar so air can flow but moisture stays in. Set it on a windowsill and have students take a daily photo and write a short observation for two weeks. By day 14, mold and bacteria are visible, the food is breaking down, and students can connect what they see to the role decomposers play in returning matter to the soil. Discuss why an ecosystem without decomposers would pile up with dead organisms forever.

Materials: Clear glass jar, banana or bread slice, small amount of soil, plastic wrap with holes, student journals or tablets for daily observation

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Texas Science Teacher Resource Hub

🚀 Jump to Your Grade

7th Grade TEKS Standards

Diagram Trophic Levels

💡 What This Standard Actually Means

⚠️ Misconceptions Your Students May Have

📓 Teaching Resources for 7.12A

🌎 Phenomenon Ideas for 7.12A

Wolves Change the Rivers in Yellowstone

Why Are There So Few Eagles Compared to Grasshoppers?

A Fallen Log in the Texas Woods

💡 Free Engagement Ideas for 7.12A

Yarn Food Web

Build the Energy Pyramid

Trophic Level Sorting Challenge

Decomposer Time-Lapse

Year-at-a-Glance Pacing Guides

Trusted Across Texas

Texas Schools and DistrictsLove Kesler Science

What Teachers Are Saying

Give Your Science Teachers Everything They Need

See It in Action

Texas Schools and Districts
Love Kesler Science