How to teach food webs

Why this matters

A student who knows that sharks eat fish can still draw the arrow from the shark to the fish, because "the shark eats the fish". In a food web the arrow shows where the energy goes, so her whole web runs backwards. She also expects that taking one animal away changes only that animal. Both mistakes look like finished work on a worksheet, and the teacher has to wait for quiz day to find out.

Food webs

A food web links all the food chains in a habitat, and each food chain is one path that energy and nutrients take through the ecosystem (National Geographic Education). Each arrow points from the food to the eater, the direction the energy moves, so "the shark eats the fish" is drawn from the fish to the shark. The living things in a food web depend on each other, so losing one animal changes animals it never eats. In a kelp forest, sea otters eat sea urchins and sea urchins eat kelp. When the otters disappear, the urchins can eat the whole kelp forest (National Geographic Education).

In this food web activity, Sparky builds a food web in a habitat where the student's favorite animal lives, and the student draws the arrows by dragging from one card to another. On a worksheet, a backwards arrow gets marked wrong. In the chat, Sparky asks the student where the energy goes, and the student turns the arrow around. Then the student predicts what will happen, presses a button that takes one animal out, and explains the chart of how each animal's numbers changed.

Maya's chat: sharks in a kelp forest

Maya loves sharks and can name what most ocean animals eat. She draws every arrow from the eater to its food, and she thinks the rest of a food web stays the same when one animal disappears.

The whole class gets the same activity: the same greeting, the same steps and a food web to draw arrows on. Each student's chat is their own. The activity's guidelines tell Sparky to build the web in a habitat where the student's favorite animal lives, and Sparky's next message depends on what the student just wrote.

Sparky uses the student's interestSparky asks a question instead of fixing the mistakeA right answer gets a harder question

M

Maya

Interest: SharksStarting point: Knows what ocean animals eat, draws arrows from eater to food

Sparky

Hi! Today you'll build a food web and find out what happens when one animal disappears. First, what's your favorite animal?

Maya

sharks!! they are my favorite

Sparky

Sharks live in kelp forests in the Pacific Ocean, so we'll build your food web there. Drag from one card to another to draw an arrow. Start with what your shark eats, then tell me which arrows you drew.

Maya

i drew shark to small fish and shark to harbor seal because the shark eats them

Sparky

You've connected the right animals. When a shark eats a small fish, where does the energy go: to the shark, or to the fish?

Maya

to the shark i guess? because it ate the fish

Sparky

Right, the energy moves into the shark. Arrows in a food web show where the energy goes. So which way should your arrow point: from the shark to the fish, or from the fish to the shark?

Maya

from the fish to the shark. i flipped them and drew more. now its sun to kelp to sea urchin to sea otter, and small fish to harbor seal to shark

Understanding check

Yes: the arrow points from the food to the eater. Before you press Remove Sea Otter, what do you predict will happen to the other animals when the sea otters disappear?

Maya

i think the urchins and crabs will be fine, and nothing else changes because the otter is just one animal

Sparky

Interesting prediction! Now press Remove Sea Otter and tell me what the chart shows happened to each animal.

Maya

whoa the sea urchins went way up to like 400 and the giant kelp almost disappeared. the small fish went down too. but the otters dont even eat kelp??

Sparky

You noticed something important. The otter never touches the kelp, so why did the kelp almost disappear? Look at your arrows: what eats the kelp, and what was keeping that animal in check?

Maya

oh! the sea urchins eat the kelp, and the otters were eating the urchins. so with no otters there are tons of urchins and they eat all the kelp

Sparky

That's a chain reaction. The shark never eats kelp either. Can you explain why the shark's numbers changed when the otters disappeared?

Maya

the small fish went down, so the harbor seals have less to eat, and the shark eats the seals. so the shark goes down a little too

Sparky

You followed the arrows all the way up to the shark. You can draw a food web's arrows to show where the energy flows, and trace how losing one animal changes animals it never touched.

Fixed her own arrows, then traced why the kelp and the shark changed

Maya drew her arrows the way she says it out loud: the shark eats the fish. Sparky didn't tell her the arrows were backwards. It asked where the energy goes, and Maya turned the arrows around herself. When the chart surprised her, Sparky sent her back to the arrows she had drawn instead of explaining the kelp.

Maya is an example student, and Sparky's replies are shortened.

What Flint did for Maya

• Sparky picked a kelp forest because Maya likes sharks, and built a food web she could draw her own arrows on.
• When Maya pointed her arrows from the shark to its food, Sparky asked where the energy goes instead of fixing them.
• Sparky asked Maya to predict what would happen before she pressed the button that takes the sea otters out.
• When Maya didn't see why the kelp disappeared, Sparky sent her back to her own arrows.
• After Maya explained the kelp, Sparky asked a harder question: why did the shark change too?

A teacher can't do this by hand for 30 students, and Sparky does it in every student's chat.

Who thinks one missing animal changes nothing else

When students finish, Sparky reads every chat and sums up the class on the activity page. The teacher sees who is stuck right now, which mistake came up most, and what to practice next.

Set up the activity for free

The food web activity is in Flint's public library, with Sparky's guidelines, greeting and greeting suggestions already written. Open it, select Use activity to copy it into a free Flint account, and move it to a class. In the activity's Preview tab, select Try session myself to test it as a student before you assign it.

For more science activities, see Flint for science.