Math bell ringers are the easiest ones to get right and the easiest ones to get wrong. Get them right and kids walk in, grab a pencil, and they’re doing math before you’ve even closed the door. Get them wrong and it’s a ten-minute mini-lesson nobody asked for.

The trick is simple: one problem, maybe two, on something they’ve already learned. A bell ringer isn’t the place to introduce something new. It’s where you keep old skills from rusting.

Below are 40 math bell ringers, 20 for middle school and 20 for high school. Every answer is worked out and double-checked. The answer keys sit under each section so you can project the problems without giving anything away.

How to use math bell ringers

  • Spiral old skills. Mix in problems from three weeks ago, not just yesterday. That’s how stuff actually sticks.
  • Ask “how did you get that?” Have one kid explain their steps out loud. You’ll catch more mistakes in that 60 seconds than in a whole worksheet.
  • Keep the numbers friendly. The point is the concept, not the long division.
  • Two problems max. If they need a calculator and ten minutes, save it for the lesson.

Math bell ringers for middle school (grades 6–8)

  1. A class has 32 students. Three-fourths of them turned in their homework. How many did not turn it in?
  2. A $60 jacket is on sale for 20% off. What’s the sale price?
  3. Solve: 7 × 8 − 6 ÷ 2
  4. A rectangle is 9 units long and 4 units wide. Find its area and its perimeter.
  5. The ratio of boys to girls in a club is 3:5. There are 32 kids in the club. How many are boys and how many are girls?
  6. Solve for x: 2x + 5 = 17
  7. Find the mean of these test scores: 4, 8, 9, 11, 13
  8. Simplify: −7 + 12 − (−3)
  9. Write 0.25 as a fraction and as a percent.
  10. A car drives 180 miles in 3 hours. What’s its speed in miles per hour?
  11. Which is bigger, 2/3 or 5/8? Show how you know.
  12. A recipe uses 3 cups of flour to make 12 cookies. How much flour for 30 cookies?
  13. Find the median: 7, 3, 9, 1, 5, 8
  14. A triangle has a base of 10 cm and a height of 6 cm. What’s its area?
  15. Evaluate 3a − 2b when a = 4 and b = 5.
  16. Your restaurant bill is $40. How much is a 15% tip?
  17. A circle has a diameter of 10 inches. Using 3.14 for π, what’s its circumference?
  18. Simplify the fraction 18/24.
  19. It’s −5°F in the morning. The temperature rises 12 degrees by noon. What’s the temperature at noon?
  20. Four notebooks cost $10. At the same price, how much do six notebooks cost?
Answer key: grades 6–8
  1. 8. 3/4 of 32 is 24 turned in, so 32 − 24 = 8 didn’t.
  2. $48. 20% of $60 is $12, and $60 − $12 = $48.
  3. 53. Multiply and divide first: 56 − 3 = 53.
  4. Area 36 square units, perimeter 26 units. 9 × 4 = 36; 2(9 + 4) = 26.
  5. 12 boys, 20 girls. 3 + 5 = 8 parts, 32 ÷ 8 = 4 per part.
  6. x = 6. Subtract 5: 2x = 12, then divide by 2.
  7. 9. 4 + 8 + 9 + 11 + 13 = 45, and 45 ÷ 5 = 9.
  8. 8. −7 + 12 = 5, and subtracting −3 means adding 3.
  9. 1/4 and 25%.
  10. 60 mph. 180 ÷ 3 = 60.
  11. 2/3. With a common denominator of 24: 16/24 vs. 15/24.
  12. 7.5 cups. 30 cookies is 2.5 times 12, and 3 × 2.5 = 7.5.
  13. 6. In order: 1, 3, 5, 7, 8, 9. The middle two are 5 and 7, so (5 + 7) ÷ 2 = 6.
  14. 30 square cm. ½ × 10 × 6 = 30.
  15. 2. 3(4) − 2(5) = 12 − 10.
  16. $6. 10% is $4 and 5% is $2.
  17. 31.4 inches. C = πd = 3.14 × 10.
  18. 3/4. Divide both by 6.
  19. 7°F. −5 + 12 = 7.
  20. $15. One notebook is $2.50, and 6 × $2.50 = $15.

Math bell ringers for high school (grades 9–12)

  1. Solve: 3(x − 4) = 2x + 5
  2. Find the slope of the line through (2, 3) and (6, 11).
  3. Factor: x² + 7x + 12
  4. A right triangle has legs of 9 and 12. How long is the hypotenuse?
  5. If f(x) = 2x² − 3, find f(−2).
  6. You put $500 in an account that pays 4% simple interest per year. How much interest do you earn in 3 years?
  7. You roll two fair six-sided dice. What’s the probability the sum is 7?
  8. Solve the system: x + y = 10 and x − y = 4
  9. Simplify: (2³ · 2⁴) ÷ 2⁵
  10. A circle has a radius of 5. Find its area in terms of π.
  11. Solve: |x − 3| = 5
  12. Rewrite 2y − 4x = 6 in slope-intercept form. What are the slope and y-intercept?
  13. Solve: x² = 49
  14. A bacteria colony starts with 50 cells and doubles every hour. How many cells after 4 hours?
  15. Find the 10th term of the sequence 5, 9, 13, 17, …
  16. Simplify √72.
  17. A cylinder has a radius of 3 and a height of 10. Find its volume in terms of π.
  18. A $20,000 car loses 10% of its value every year. What’s it worth after 2 years?
  19. Solve: 2^x = 32
  20. Find the distance between (1, 2) and (4, 6).
Answer key: grades 9–12
  1. x = 17. 3x − 12 = 2x + 5, so x = 17.
  2. 2. (11 − 3) ÷ (6 − 2) = 8 ÷ 4.
  3. (x + 3)(x + 4). Two numbers that multiply to 12 and add to 7.
  4. 15. 9² + 12² = 81 + 144 = 225, and √225 = 15.
  5. 5. 2(4) − 3 = 5.
  6. $60. $500 × 0.04 × 3 = $60, so the account holds $560.
  7. 1/6. Six of the 36 outcomes add to 7: (1,6), (2,5), (3,4), (4,3), (5,2), (6,1).
  8. x = 7, y = 3. Add the equations: 2x = 14.
  9. 4. Add exponents on top (2⁷), subtract the bottom: 2² = 4.
  10. 25π. A = πr² = π(5²).
  11. x = 8 or x = −2. x − 3 = 5 or x − 3 = −5.
  12. y = 2x + 3. Slope 2, y-intercept 3.
  13. x = 7 or x = −7. Don’t forget the negative.
  14. 800 cells. 50 → 100 → 200 → 400 → 800.
  15. 41. It goes up by 4 each time: 5 + 9(4) = 41.
  16. 6√2. √72 = √36 · √2.
  17. 90π. V = πr²h = π(9)(10).
  18. $16,200. $20,000 × 0.9 = $18,000, then × 0.9 again.
  19. x = 5. 2⁵ = 32.
  20. 5. √((4 − 1)² + (6 − 2)²) = √(9 + 16) = √25.

Make your own math bell ringers

Running out? Here’s a formula that works in any math class:

  • Monday: one from last week. Pull a problem straight from the last quiz.
  • Tuesday: find the mistake. Show a worked problem with one error. Kids have to find and fix it. They love catching the “teacher” messing up.
  • Wednesday: real life. A sale price, a tip, a gas mileage question.
  • Thursday: estimate first. “About how much is 19 × 21?” before they calculate.
  • Friday: which one doesn’t belong? Four numbers or graphs, and they argue which is the odd one out. There’s usually more than one right answer, which is the fun part.

Get a new math bell ringer every day

Every school day we post a new set of bell ringers with a math problem for grades 6–8 and one for grades 9–12, with the worked answer in a collapsed box. Each set also has ELA, science, social studies, and current events. Free, no sign-up.

More lists: 100 bell ringer questions, science bell ringers, social studies bell ringers, and grammar bell ringers.

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