OpenField Finance

Beginner Course · Lesson 11 Assessment

Assessment: Avoiding Common Money Mistakes Teens Make

Check what you understood from Lesson 11 and apply it to real life.

Beginner Lesson 11 of 14
Before you start: complete the questions and challenges first. The full answer key with explanations is at the bottom of this page — no peeking until you finish.

1. Knowledge Check

1. What is opportunity cost in a financial decision?
  1. The total price including taxes
  2. What you give up when you choose one option
  3. The fee charged by a bank
  4. The discount you miss during a sale
2. Marcus gets a raise and immediately increases his spending. Which mistake is this?
  1. Subscription blindness
  2. Lifestyle inflation
  3. Emergency fund failure
  4. Debt avalanche
3. Sofia cancels unused subscriptions and saves $27.97/month. About how much is that per year?
  1. $167.82
  2. $279.70
  3. $335.64
  4. $419.55
4. Which habit best prevents impulse buys over $30?
  1. The 24-Hour Rule
  2. The Raise Rule
  3. Only using cash forever
  4. Skipping all wants
5. Why is waiting to start saving so expensive?
  1. Banks charge extra fees to young savers
  2. Inflation makes every purchase illegal
  3. You lose time for compound growth
  4. Savings accounts stop working after age 18

Short Answer

6. Explain opportunity cost using a teen-related example.

Write 2–4 sentences.

7. Choose one of the 10 mistakes and describe a replacement habit that could prevent it.

Write 2–4 sentences.

2. Real-World Action Challenge

The Mistake Audit and Two-Habit Commitment

Objective: Identify your two biggest financial weak spots and replace each with one realistic habit.

  1. Rate yourself 1–5 on each of the 10 mistakes.
  2. Circle your two lowest scores.
  3. For each weak spot, write one habit using: When [trigger], I will [action].
  4. Calculate the opportunity cost of one recurring habit.
  5. Do a subscription audit this week and redirect any savings.
Reflection Question: Which habit change would save you the most stress or money over the next 60 days, and why?

3. Extension Challenge

Choose one recurring spending habit. Calculate its monthly cost, annual cost, five-year cost, and estimated five-year value if saved at 4.5% APY. Then write a short recommendation: keep it, reduce it, or redirect it.

4. Key Takeaways

  • Money mistakes are usually behavior problems, not intelligence problems.
  • Opportunity cost helps you see the real trade-off behind spending.
  • Small recurring habits can cost hundreds or thousands over time.
  • Systems like automation, audits, and Money Monday beat willpower.
  • Start now, even small. Time is the biggest advantage teens have.

Answer Key

1. Correct Answer: B

Opportunity cost is the value of what you give up when you choose one thing over another.

2. Correct Answer: B

Lifestyle inflation happens when spending rises to match income increases.

3. Correct Answer: C

$27.97 × 12 = $335.64.

4. Correct Answer: A

Waiting 24 hours adds friction and helps make the purchase intentional.

5. Correct Answer: C

Starting earlier gives money more years to grow and earn returns on returns.

6. Sample Guidance

A strong answer explains both what is purchased and what goal is delayed or sacrificed.

7. Sample Guidance

A strong answer names the mistake and gives a specific replacement behavior with a trigger.

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