Tock's Think Twice Book
Ask good questions. Check the proof. Make up your own mind.
What is critical thinking?
Critical thinking means not believing something just because someone said it. You ask questions, look for proof and then decide.
It isn't about being grumpy or saying "no" to everything. Critical thinkers are curious. They ask "How do you know?" in a friendly way, and they are happy to change their mind when the evidence is good.
Today, words, pictures and videos can be made in seconds, by people or by AI. That makes this one of the most useful skills you can have. This book gives you eight of them.
How this book works
Every chapter has the same four parts.
- Read it. One big idea, with pictures.
- Try it. An activity you play right here on the screen.
- Away from the screen. A game for paper, pencils and friends.
- Quick check. Three questions. Get them all right to earn a star.
There are 9 stars to collect. Got a question wrong? No problem. Read the hint and have another go. That's how thinkers learn.
Choose a chapter
Chapter 1 · Thinking skill one
Fact or opinion?
Every day you hear hundreds of claims. "It's going to rain." "This is the best game ever." "Sharks never sleep." The first skill is sorting them.
A fact is a claim you can check. You can measure it, count it, look it up or test it. "A spider has eight legs" is a fact. You could count them.
An opinion is what someone thinks or feels. "Spiders are scary" is an opinion. Nobody can check it, because people feel differently, and that's fine.
Sort each claim. Ask yourself: could someone check this?
Away from the screen: the highlighter hunt
You need: a cereal box, catalogue or magazine and two coloured pencils
Find something with lots of writing on it, like a cereal box. Underline facts in one colour and opinions in another. Which colour wins? What does the box want you to feel?
Quick checkEarn your star
Chapter 2 · Thinking skill two
Who says so?
Information doesn't fall from the sky. Someone made it. The person, book, website or video it came from is called the source.
Some sources know a lot about a topic and try hard to get it right. Others are guessing, joking, or trying to sell you something. A critical thinker checks the source before trusting the claim.
Someone who has studied or worked on a topic for years is called an expert. A vet is an expert on sick pets. A famous singer is an expert on singing, but not on sick pets.
For each question, choose the source you would trust most.
Away from the screen: trace it back
You need: paper and a pencil
Write down three things you believe are true, like "carrots help you see in the dark" or "goldfish have a three-second memory". For each one, write where you first heard it. Can you find a better source to check it? You may be surprised.
Quick checkEarn your star
Chapter 3 · Thinking skill three
Where's the proof?
A claim without evidence is just someone talking. Evidence is what makes a claim worth believing.
Not all evidence is equally strong. "My cousin said so" is weak. "We measured it twenty times and wrote down the results" is strong.
Strong evidence has three things. There is enough of it, not just one example. It was collected fairly. And other people could check it and get the same answer.
In maths: sample size
If you ask 2 people their favourite sport, you learn about 2 people. If you ask 200, you learn about your school. The number of people you ask is called the sample size, and bigger is usually better.
Read the claim and the evidence. Is the evidence strong or weak?
Away from the screen: test a claim
You need: a ruler or tape measure, six people and a table to write in
Claim: "People with longer feet are taller." Don't argue about it. Test it. Measure the foot length and height of six people and write the numbers in a table. Does the evidence support the claim? Is six people enough to be sure?
Quick checkEarn your star
Chapter 4 · Thinking skill four
Does it follow?
Good thinking is a chain: evidence, then a reason, then a claim. If a link is missing, the chain breaks.
"The ground is wet, so it rained." Does that follow? Maybe. But a sprinkler, a burst pipe or a spilled bucket would also make the ground wet. A critical thinker asks, "What else could explain this?"
The trickiest broken link is mixing up together with because. On days when lots of ice creams are sold, lots of people get sunburnt. Does ice cream cause sunburn? No. Hot sunny weather causes both.
Does the reason really support the claim, or is it a leap?
Away from the screen: what else could it be?
You need: a partner
Take turns. One person says something they noticed, such as "The cat is hiding under the bed." The other gives three different explanations. Then decide together: how could you find out which one is right?
Quick checkEarn your star
Chapter 5 · Thinking skill five
Spot the trick
Ads, posters and videos are often built to persuade you. That's not always bad. But you should notice when it is happening.
Persuaders have a toolbox of tricks. The tricks work by making you feel something fast, so you don't stop to think. Once you know them, you'll see them everywhere.
This ad for a made-up drink has five tricks and one plain fact. Tap each line to inspect it. Can you find all five tricks?
ZAPPO FIZZ
Away from the screen: trick collector
You need: a catalogue, some junk mail, scissors and glue
Cut out three ads. For each one, write which trick it uses. Then write what the ad does not tell you, such as the price, the size or what's inside.
Quick checkEarn your star
Chapter 6 · Thinking skill six
See both sides
Draw a 6 on the ground. Stand on the other side. Now it's a 9. Who is right? Both of you, from where you stand.
Most real questions are like that. Should the class get a pet? The kids who love animals see one side. The kid with allergies sees another. The cleaner sees a third.
A fair thinker can explain the other side so well that the other side says, "Yes, that's what I mean." You don't have to agree. You do have to understand.
Leaning one way before you've looked at the evidence is called bias. Everyone has some. The trick is to notice your own.
Does each report show both sides, or only one?
Away from the screen: the switch debate
You need: a partner and a timer
Pick a friendly topic, like "Should school start an hour later?" Argue one side each for one minute. Then switch sides and argue the opposite. Which was harder? Did you change your mind about anything?
Quick checkEarn your star
Chapter 7 · Thinking skill seven
Real or fake?
Online, anyone can post anything. Photos can be changed. Pictures, voices and videos can be made by AI. Headlines are written to make you click.
You don't have to become suspicious of everything. You just need a routine, like looking both ways before crossing the road.
Stop. Does it make you feel shocked, angry or amazed? Strong feelings are a warning light. Look closer. Who posted it? When? Do the details look odd? Check elsewhere. Do other trusted sources say the same thing? Ask. A parent, teacher or librarian can help.
Would you trust each one as it is, or check it first?
Away from the screen: two truths and a fake
You need: an animal book or encyclopedia, paper and friends
Write two amazing true facts about an animal and one fake that you made up. Read them out. Your friends must work out which is fake, then verify it by finding the truth in a book.
Quick checkEarn your star
Chapter 8 · Thinking skill eight
Change your mind
Here is a secret about smart people. They change their minds a lot. Not because they are weak, but because they keep learning.
People once believed the Sun went around the Earth. Better evidence showed it was the other way round. Saying "I was wrong" is how every one of us gets closer to being right.
It helps to stop thinking in only two boxes, true and false. Think about how sure you are.
In maths: the language of chance
Words like impossible, unlikely, even chance, likely and certain put a size on how sure you are. Each new clue should nudge you along the scale.
Someone ate the biscuits. After each new clue, choose who is the most likely suspect right now. Be ready to change your mind.
Away from the screen: I used to think
You need: paper and a pencil
Finish this sentence three times: "I used to think ___, but now I think ___, because ___." Share one with someone at home. Ask them for one of theirs.
Quick checkEarn your star
The last chapter · Put it all together
The big think
You now have all eight thinking skills. Here they are, with the question each one asks.
| Skill | Ask yourself |
|---|---|
| Fact or opinion? | Could someone check this? |
| Who says so? | Who made this, and why? |
| Where's the proof? | What is the evidence, and is there enough? |
| Does it follow? | What else could explain this? |
| Spot the trick | Is someone trying to rush or flatter me? |
| See both sides | How does this look from the other side? |
| Real or fake? | Have I checked this somewhere else? |
| Change your mind | How sure am I, and what would change that? |
Before you go, show what you know. Answer all ten questions to earn your last star and your certificate.
Final testTen questions, every skill
Certificate of Critical Thinking
This certificate is proudly given to
for learning to question claims, weigh evidence and think it through.
Look it up
Word bank
Every big word in this book, in plain language.
- Bias
- Leaning one way before you have looked at the evidence.
- Cause
- The thing that makes something else happen.
- Claim
- Something a person says is true.
- Evidence
- Information that helps show whether a claim is true.
- Expert
- Someone who has studied or worked on a topic for a long time.
- Fact
- A claim that can be checked.
- Open-minded
- Willing to change what you think when you get better evidence.
- Opinion
- What someone thinks or feels.
- Persuade
- To try to get someone to believe or do something.
- Point of view
- How things look from where someone stands.
- Reason
- The "because" that connects evidence to a claim.
- Sample size
- How many people or things you checked.
- Source
- Where a piece of information comes from.
- Verify
- To check that something is true before you believe it or share it.
Parents, carers and teachers
Notes for grown-ups
Critical thinking is the habit of asking "How do we know?" before accepting a claim. With so much text, imagery and video now produced instantly, including by AI, children need a calm routine for checking what they see.
The tone of this book is curious, not cynical. The aim is a child who asks friendly questions and can say "I've changed my mind". Chapter 4 (cause and coincidence) is the most demanding and suits ages 9 and up.
How to use the book
- One chapter per sitting. Each takes about 15 to 25 minutes, plus the off-screen activity.
- Ages 7 to 8 will get more from it with someone reading alongside. Ages 9 to 12 can usually work alone.
- Chapters build on each other, so going in order works best.
- Wrong answers are part of it. Every quiz question explains itself and can be tried again.
- Stars are saved in this browser on this device. Clearing browser data may reset them.
What each chapter covers
| Chapter | Idea | Where it helps at school |
|---|---|---|
| 1. Fact or opinion? | Claims, facts and opinions | Reading comprehension, persuasive texts |
| 2. Who says so? | Sources, expertise and purpose | Research skills, library and online searching |
| 3. Where's the proof? | Strength of evidence, sample size | Data and statistics, science investigations |
| 4. Does it follow? | Reasoning, cause and coincidence | Science explanations, maths reasoning |
| 5. Spot the trick | Persuasive techniques | Media literacy, analysing advertisements |
| 6. See both sides | Perspectives and bias | Discussion and debate, history sources |
| 7. Real or fake? | Verifying online information | Digital literacy, online safety |
| 8. Change your mind | Open-mindedness, degrees of certainty | Chance and probability language |