Teaching Sequence

Work through this resource material in the following sequence:

15 minutes

Tune In: Introducing food chains, food webs and trophic levels

20 minutes

Find Out: Lions in the food web

20 minutes

Take Action: Communicating lion conservation

5 minutes

Reflection

Learning intentions

Students will:

explore food chain and food web models and how they relate to trophic levels
know that lions are apex predators with a vital role in the food web
recognise that lion conservation actions aim to protect both lions and the ecosystems they live in.

Students can:

explain why lions are vital to the food web and how their loss would impact the whole ecosystem
communicate some of the science behind lion conservation.

Prior Knowledge: Some prior knowledge of food chains, food webs and trophic levels could be useful for this lesson but is not essential.

Begin by inviting students to share what they already know about food chains and food webs. For example:

A food chain is a linear representation of how organisms get energy and pass energy on to other organisms. A food chain shows just one line of energy transfer, for example, from flower to butterfly to bird
A food web is a linear representation of how organisms within an ecosystem receive and transfer energy. It is a more complex representation as it shows a range of organisms and how they all interact with one another. An example of a food web could be a grassland ecosystem where plants, insects, reptiles, mammals and birds all interact with one another and transfer energy.

Share the following images with students and invite them to explain what these images represent and what they think is happening in each image:

You can use the following points to guide your discussion around these images:

You can use the following points to guide your discussion around these images:

Food chain

Plants are at the beginning of the food chain and they get their energy from sunlight. The browsing animal gets its energy from eating the plants. The predators get their food from eating other animals.
We can use an arrow to show the feeding relationships between organisms. It is important to note that the arrow always points to the organism that has just consumed something, as this shows the flow of energy.

Food web

You can see from the food web that the flows of energy go in all sorts of directions and weave and wind around each other.
You can also see that generally, the smaller organisms at the bottom of the food web have a greater number of predators, and the number of predator-prey relationships decreases the further up the food web you go.

You could also share this video (youtube.com/watch?v=2lqhJNgn_Wg) with students if more information is required.

Now share the following image with students:

Invite students to suggest what they think this image explains and how it relates to a food chain or web, for example:

The living things in a food web can be grouped into categories called trophic levels. Generally speaking, trophic levels can be divided into decomposers, producers, and consumers.
The producers are found at the bottom of the food web and include organisms like trees, shrubs, mosses and grasses. These organisms convert sunlight into energy through photosynthesis.
In the next stage, there are primary consumers. This level includes many insects, mammals, and birds that eat plants, their seeds, and their fruit.
At the next level are the secondary consumers. These organisms are omnivourous or carnivorous. This level includes the apex predators, those who are at the very top of the food chain and who don’t have predators of their own.
Decomposers break down dead plant and animal materials and waste and convert it to energy. These include bacteria, fungi and insects like termites.