Grades 3–5

Becoming a Neural Network

This week we find out what's inside an AI, then become one.

Day 1

A human neural network

Computers make predictions

A prediction is a guess about something we don't know yet, made from something we do know.

🌧️

Weather

The weather app says it will rain.

📺

Videos

A video site picks your next video.

💬

Words

A phone guesses your next word.

Where has a computer made a prediction for you?

Elementary School · Grades 3–5

Let's make a prediction

A zoo gets more visitors when it's sunny.

1 hour of sun → 200 visitors
3 hours of sun → ?600 visitors

How did you know? You multiplied 3 × 200.

That is exactly what a neural network does!

Elementary School · Grades 3–5

Words to know

AI
Computer programs that do things that usually take human thinking.
Prediction
A guess about something we don't know yet.
Neural network
A kind of AI that passes numbers along connections and multiplies them.
Input value
The number that goes into the network.
Connection
The line that carries a number from an input to an output.
Weight
The number on a connection. The input is multiplied by it.
Output value
The number that comes out: the network's prediction.

Elementary School · Grades 3–5

Become a neural network!

3

Input

Writes down the hours of sun and passes it on.

×

Connection

Holds the weight card, × 200, and multiplies.

!

Output

Announces the prediction.

Now swap the weight card for × 150. What will change?

Elementary School · Grades 3–5

Activity

Find the three parts in the app

The Zoo Visitors Predictor 01 Forward Propagation tab ↗
  1. Point to the input value.
  2. Point to the weight.
  3. Point to the output value.
  4. Step through all four inputs.
200 3 hours of sun ?600 visitors

Elementary School · Grades 3–5

Let's talk

  1. Which job in our human network was the most important?
  2. What happened when we changed the weight card?
  3. How is the app like our human network? How is it different?

Elementary School · Grades 3–5

Day 2

Predict, then check

Crickets are thermometers

Crickets chirp faster when it's warmer: about 6 more chirps a minute for every degree.

How could a network turn the temperature into chirps?

With a weight of 6!

Elementary School · Grades 3–5

Words to know

Predict
To work out an answer before you see it.
Check
To compare your prediction with the real answer.
Growth rate
How much bigger something gets each year.

Elementary School · Grades 3–5

Activity

Predict the cricket chirps

The Cricket Chirp Predictor Forward Propagation tab ↗

Crickets chirp faster when it's warm: 6 more chirps for every degree. So the weight is 6.

  1. Work out the output on paper.
  2. Type in your prediction.
  3. Step on to check.
6 15 degrees ?90 chirps

Say your multiplication out loud to your partner!

Elementary School · Grades 3–5

Spot the pattern

degrees15202530
chirps90120150180

What do you add each time? Why does that work?

Each input is 5 degrees warmer, and 5 × 6 = 30.

Elementary School · Grades 3–5

Explore

Watch a tree grow

The Tree Growth Predictor 01 Sample Networks tab ↗

The tree's weight is 1.27, its growth rate.

a 10-meter tree next year: ?12.7 meters

What does a weight bigger than 1 do to the input?

Elementary School · Grades 3–5

Let's talk

  1. How many chirps would the network predict at 10 degrees? At 40?
  2. The tree network's weight is 1.27. What would a weight of 1 mean?
  3. Why is it useful to predict before you check?

Elementary School · Grades 3–5

Day 3

Fixing a network that's wrong

Today the weights are wrong!

🤔

Output value

The network's guess.

🎯

Target output

The real answer: what actually happened.

✅

A match

When the guess and the real answer match, the lines turn green.

Your job: fix the weights!

Elementary School · Grades 3–5

Words to know

Target output
The real answer. The output should match it.
Tuning
Changing a weight, a little at a time, until the outputs match the targets.

Elementary School · Grades 3–5

Activity

Fix the phone battery

The Phone Battery Predictor Forward Propagation tab ↗

The weight is wrong! A 1-hour video really uses 12% of the battery.

  1. Click the weight. Change it.
  2. Step through all four videos.
  3. Green lines mean it matches!
5 1 hours 5 battery % 12 target

Too big or too small? Should the weight go up or down?

Elementary School · Grades 3–5

Activity

Two outputs, two weights

The Smoothie Stand Predictor Forward Propagation tab ↗

One input, the temperature, now makes two predictions: smoothies and popsicles.

Each output has its own weight. Find both!

11 1 degrees 1 smoothies 1 popsicles

Elementary School · Grades 3–5

Count the tries

Keep a tally of how many tries each weight took you.

Did anyone find a shortcut?

Divide the target by the input: 12 ÷ 1 = 12.

Elementary School · Grades 3–5

Let's talk

  1. How did you know which way to change the weight?
  2. Who found the weight in the fewest tries? How?
  3. A real AI does what you did, millions of times. What is it doing each time?

Elementary School · Grades 3–5

Day 4

Two inputs at once

Two inputs at once

What decides how many butterflies visit a garden? Often more than one thing.

Multiply each input by its weight, then add.

3 × 1 + 4 × 2 = ?11
12 3 flower beds 4 bushes ?11 butterflies

Elementary School · Grades 3–5

Words to know

Input values
The numbers that go in. A network can have more than one.
Connection
The line that carries a number from an input to an output.
Total
Each input times its weight, added together.

Elementary School · Grades 3–5

Activity 1

One weight to change

The Butterfly Count Predictor Forward Propagation tab ↗

Make each bush count twice as much as each flower bed.

  1. The flower bed weight is already 1.
  2. What should the bush weight be? Change it.
  3. Check it works for all four gardens.

Elementary School · Grades 3–5

Activity 2

Both weights to find

The Tomato Harvest Predictor Forward Propagation tab ↗

Find the weight for each hour of sun and each liter of water. Both are between 0 and 1.

½

0.5 is a half

Like half a pizza.

¼

0.25 is a quarter

Like a quarter of a pizza.

1

One at a time

Change one weight, then check.

Elementary School · Grades 3–5

Put the weights into words

Write down what each tomato weight means.

0.5: ?half a kilogram of tomatoes for each hour of sun
0.25: ?a quarter for each liter of water

Elementary School · Grades 3–5

Let's talk

  1. In the tomato garden, which matters more: an hour of sun or a liter of water?
  2. What does a bigger weight tell us about an input?
  3. Why was this harder than one input?

Elementary School · Grades 3–5

Day 5

Design your own network

What does each weight mean?

The Honey Harvest Predictor Sample Networks tab ↗

The Honey Harvest Predictor's inputs are the flowers nearby and the days in the month.

0.28: ?kilograms of honey for each flower
0.45: ?kilograms for each day

Today, you design a network of your own!

Elementary School · Grades 3–5

Words to know

Data
Real numbers collected from the world, to check whether a network's predictions are right.
Design
To plan something before you build it: its inputs, output and weights.

Elementary School · Grades 3–5

Activity

Design your own network

  1. Draw a network from your own life, with one or two inputs and one output.
  2. Label each input, the output and each weight.
  3. Make a table of three rows: the inputs, and the output.
  4. Swap with a partner and predict each other's outputs.

Ideas: minutes of reading and pages read, hours of practice and goals scored.

Elementary School · Grades 3–5

Let's talk

  1. How did you choose your weights?
  2. How could you find out whether your weight is right?
  3. What would you want a computer to predict, if you could build any network?

Elementary School · Grades 3–5

A neural network is…

Walk the gallery: predict one output on each network.

Then finish the sentence on a sticky note: "A neural network is…"

Keep exploring at iinnoo.app

Elementary School · Grades 3–5