?what's that tax?
Student lessonsAI literacy

For high school · About 15 minutes

AI in real life

Choose an activity to begin. After the four activities, try the final challenge.

Activity 1 of 4 3 min

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Check the receipt

Predict

Would you pay €24 or €28? Read what the chatbot says, then look for the clue on the receipt.

Try

JordanCan you read this receipt? What did I pay?

Sample chatbot“You owe €28. I added €4 VAT to the €24 total.”

Select the line that settles it.

Hoodie receipt

Price before VAT
€20
VAT included
€4
Total paid
€24
Compare with a correction

You paid €24. The receipt says the €4 VAT is included, so adding it again counts it twice.

Try a different receipt

A receipt says €30 total, including €5 VAT. What did you pay? Explain why in one sentence.

See the answer and 20-second walkthrough

You paid €30. The €5 VAT is already part of the total.

Read the transcript

A chatbot reads a receipt and says you owe thirty-five euros. Let’s check. The receipt lists five euros of included VAT. That word, included, matters. The total says thirty euros. That’s the amount you pay. The five euros are already in the total. Adding them again counts the tax twice.

Explain

In one sentence, explain which word tells you whether to add the VAT again.

Next activityTrain a filter →

Activity 2 of 4 4 min

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Train a filter

Predict

Will “claim class reminder” be marked spam, regular, or unsure? Guess before you test it.

Try

The filter gives each distinct word one point if it appears in just one group of training examples. Both groups get zero for shared or unseen words. A tie means unsure.

Training examples

  • Spam “claim prize”, “claim reward”
  • Regular “class update”, “class reminder”

Test messages

Pick a message. Then add the extra spam example to see the result for the same message again.

Explain

Which words stop earning points after you add the example? Try all three messages and explain why one prediction stays the same.

Compare with an explanation

“Class” and “reminder” now appear in both groups, so they stop scoring. “Claim class reminder” goes from regular to spam, and “class reminder tonight” goes from regular to unsure. “Claim prize tonight” stays spam because “claim” and “prize” still earn spam points, and the filter has never seen “tonight.”

Next activityChoose a safe prompt →

Activity 3 of 4 2 min

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Choose a safe prompt

Predict

You’re studying how to read a paycheck. Your teacher allows AI for practice. What information would you keep out of the prompt?

Try

Pick the prompt that helps you practice safely.

Explain

How would you check an AI-generated practice answer yourself?

Compare with an explanation

Solve the practice question using the fictional pay stub, then compare your result with the answer. Follow your teacher’s rules for AI use and disclosure on graded work.

Next activityAudit AI answers →

Activity 4 of 4 3 min

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Audit AI answers

Predict

Which kind of document might make a chatbot guess?

Try

The chatbot got the same instruction for each document.

“Copy the tax amount shown. If no tax amount is shown, say ‘not shown.’”

Which reply needs correcting? Choose one.

Pay stub

Document
Federal income tax withheld: $8
Sample reply
$8

Store receipt

Document
Sales tax: $2
Sample reply
$2

VAT receipt

Document
VAT included: €4
Sample reply
€4

Price tag

Document
Price: $20
Sample reply
$1

Explain

How many replies match their documents? What should the chatbot say when the information is missing?

Compare with the answer key

Three of four replies match. The price tag shows a $20 price but gives no tax amount. The chatbot should say “not shown.”

Next activityFinal challenge →

3 min

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Final challenge

Check the chatbot’s answer against this fictional pay stub.

Pay stub

Gross pay:
$120
Federal income tax withheld:
$7
Other deductions:
$10
Take-home pay:
$103

JordanHow much federal income tax came out of this paycheck?

Sample chatbot“$17. That’s the difference between gross pay and take-home pay.”

Type your answer or say it aloud before you reveal the model answer. Anything you type stays on this page.

Reveal the model answer

Correction. Federal income tax withheld was $7. The $17 difference also includes $10 in other deductions.

Evidence. “Federal income tax withheld: $7.”

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For teachers

Students can work through the 15-minute lesson on their own. In pairs, have one student predict and the other explain, then swap roles. Use the final challenge as an exit ticket and look for both a correction and an exact line of evidence.

Back to the tax mini-lessons →