Good Learning Co.
SavannahYear 8
← Science
ScienceEcosystems and interdependence25 min★ difficulty

Food webs and energy transfer

Arrows in a food chain show the direction energy travels — from the eaten to the eater. Only about 10% of energy passes to the next level.

Part of your national curriculum
  • Working scientifically: Ask questions and develop a line of enquiry based on observations of the real world
  • Working scientifically: Interpret observations and data, including identifying patterns and using observations to draw conclusions
  • Biology: material cycles and energy: Understand the reactants in, and products of, photosynthesis, and a word summary for photosynthesis
  • Biology: interactions and interdependencies: Understand the interdependence of organisms in an ecosystem, including food webs and insect pollinated crops
  • Biology: interactions and interdependencies: Understand how organisms affect, and are affected by, their environment, including the accumulation of toxic materials

Lesson overview

What you'll learn in this lesson

Construct and interpret food chains and webs

Key learning points

  • • Producers, consumers, decomposers
  • • Why chains are short

This lesson at a glance

  • 25 minutes
  • 12 parts to scroll through
  • 3 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

constructinterpretchainsproducersconsumers

Scroll down — the lesson carries on below

Part 1 of 12 · Discover8%
1

Watch & discover

Part 1 of 12

Watch first

Food webs and energy transfer

An English teaching video on this topic from Cognito. Watch it, then scroll down for the lesson.

In a nutshell

Construct and interpret food chains and webs

2

Explore the idea

Part 2 of 12

Learn

Producers, consumers, decomposers

Producers capture light energy. Consumers get energy second hand. Decomposers return nutrients to the soil, keeping the whole system running.

3

Explore the idea

Part 3 of 12

Learn

Why chains are short

With roughly 90% of energy lost at each transfer as heat and movement, there is rarely enough left to support a fifth or sixth level.

4

Explore the idea

Part 4 of 12

Worked example

Worked example — wolves in Yellowstone

Returning wolves reduced elk browsing, willow and aspen recovered, beaver numbers rose and riverbanks stabilised. One predator changed the structure of a whole ecosystem.

5

Reset break

Part 5 of 12

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
6

Quick check

Part 6 of 12

Quick check

An arrow in a food chain points…

7

Quick check

Part 7 of 12

Quick check

Roughly how much energy passes to the next trophic level?

8

Quick check

Part 8 of 12

Quick check

Removing a top predator most likely…

9

Challenge round

Part 9 of 12

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

10

Challenge round

Part 10 of 12

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

____ capture light energy.

____ get energy second hand.

11

Mastery quiz

Part 11 of 12

Marked quiz

End of lesson quiz: Food webs and energy transfer

4 questions, marked with the reasoning shown. No timer.

  1. 1. A class records that plant height increases as light hours increase, then levels off. What does the levelling off suggest?

  2. 2. An arrow in a food chain points…

  3. 3. Roughly how much energy passes to the next trophic level?

  4. 4. Removing a top predator most likely…

12

Lesson round-up

Part 12 of 12

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 12 · Watch & discover

How this is going

  • Not looked at yet

    Ask questions and develop a line of enquiry based on observations of the real world

  • Not looked at yet

    Interpret observations and data, including identifying patterns and using observations to draw conclusions

  • Not looked at yet

    Understand the reactants in, and products of, photosynthesis, and a word summary for photosynthesis

  • Not looked at yet

    Understand the interdependence of organisms in an ecosystem, including food webs and insect pollinated crops

  • Not looked at yet

    Understand how organisms affect, and are affected by, their environment, including the accumulation of toxic materials

Good Learning Co. — personalised UK curriculum learning, built around what each learner loves.