12.1 · Reading a Food Chain

From Ohio 5th Grade Science Power Workbook · Chapter 12 · Lesson 12.1.

Big idea: A food chain shows the path energy takes. The arrow points from the food to the eater.

Learning goals: Read the arrows in a food chain correctly

Explain why every chain starts with a producer

Trace the energy in a chain back to the sun

The arrow points at the eater

A food chain is a line of organisms. Each one is food for the next.

The arrow does not mean 'eats'. It shows which way the energy moves. Energy moves from the food into the eater. So the arrow points at the eater.

Grass → rabbit means the rabbit eats the grass. Energy moves from the grass to the rabbit.

Every chain starts the same way

The first living thing in a food chain is always a producer. It made its own food using the sun's energy.

That is why many food chains are drawn with the sun at the start. The sun is not food. It is where the producer's energy came from.

Everything after the producer is a consumer. Each one gets its energy from the one before it.

Worked examples

Question: A food chain is drawn as: algae → water insect → fish. What eats what, and where did the fish's energy come from?

Steps: Read each arrow as 'is eaten by'. Algae is eaten by the water insect. The water insect is eaten by the fish.

Find the producer. Algae is first, and algae makes its own food using sunlight.

Trace the fish's energy backwards. Fish, insect, algae, and then the sun.

Answer: The insect eats the algae and the fish eats the insect. The fish's energy came from the insect, which got it from the algae, which got it from the sun.

Common mistakes

The arrow is not the word 'eats'

It is tempting to read an arrow like a sentence: the first thing does something to the second.

The arrow shows where the energy goes. It leaves the food and enters the eater. So the arrow points at the one doing the eating.

Check your thinking: Put your finger on the arrowhead. Whatever it touches is the eater.

Ohio connection

A chain you can watch in an Ohio park

In a city park in Ohio, an oak drops acorns. A squirrel gathers them. A red-tailed hawk watches the squirrel from a light pole.

That is a complete food chain. Oak → squirrel → hawk, and the oak's energy came from the sun.

Think: Draw this chain with arrows. Then explain what the first arrow means in your own words.

Remember

Arrowhead touches the eater

Say 'is eaten by' every time you cross an arrow. Grass is eaten by rabbit. Rabbit is eaten by fox. You will never reverse a chain again.

Practice tip

Remember: Ohio draws the chain. You read it.

Tip: You will not be asked to memorize a chain. You will be shown one and asked what eats what, or what happens to the energy. Read every arrow as 'is eaten by' before you answer.

Written practice

A student draws: fox → rabbit → grass. Explain what is wrong and how to fix it.

Sample response: The arrows are backwards. An arrow shows energy moving from the food into the eater, so it points at the eater. The grass is eaten by the rabbit and the rabbit is eaten by the fox. The chain should be grass → rabbit → fox.

Scoring guide: 1 point: says the arrows point the wrong way, because arrows show energy moving from the food to the eater.

1 point: gives the corrected chain, grass → rabbit → fox.

Reversed arrows are the most common error on a drawn chain. The fix is always the same: point the arrow at the eater.