Subtract to Collect the Pearls Game
Kids see two fractions with the same denominator and click the shell whose value equals their difference. The right shell opens and releases its pearl; wrong shells shut closed. It's the same way Cuemath tutors introduce fraction subtraction in live 1:1 classes.
Pearls of Atlantis
Grade 4
5 min · 6 rounds
Used in Cuemath 1:1 classes
About the game
Subtract to Collect the Pearls is a free online math game for Grade 4 students learning to subtract fractions with the same denominator. An in-game tutorial introduces the underwater mechanic, then players see two fractions and pick the shell whose value equals their difference — the diver swims to the right shell and a pearl floats out. Wrong shells shut closed. Across 6 rounds, students build the core insight that subtraction with like denominators works the same way as addition: when the parts are already the same size, you only change how many you have. The denominator — the size of each part — stays put.
From the classroom
How Cuemath Tutors Use This Game
Tutors use this when a student has just got comfortable adding fractions with like denominators and is ready to confirm that subtraction follows the same rule. Pearls of Atlantis lets the student see it directly: 4/7 minus 1/7 isn't a new operation on the denominator — it's three sevenths of a pearl left after taking one of seven away.
Once a student has collected a few pearls, the question 'are the pieces the same size?' starts replacing 'is this addition or subtraction?'. Tutors often ask 'how many of the same-sized pieces did you start with, and how many did you take away?' before the student picks a shell — so the subtraction stays a count action, not a denominator action.
Often paired with
Adding fractions with like denominators before, subtracting fractions with unlike denominators after.
What students said
Students named the difference under their breath before clicking — watching the right shell open and the pearl float out, then waiting for the diver to swim across to the next pair.
Grade 4 classroom feedback
Collected across 115+ live 1:1 classes
Cuemath 1:1 classes
A Cuemath tutor can do what a game can’t — diagnose exactly where your child gets stuck on fraction operations, and sequence what comes next.
What Your Child Practices
Four dimensions from the Cuemath FUAR taxonomy — Fluency, Understanding, Application, Reasoning — applied to this game.
Fluency
Fluency in subtracting fractions with the same denominator — taking the difference of the numerators while the denominator stays put.
Understanding
Understanding that subtraction with like denominators is the same rule as addition with like denominators, run in reverse: the size of each piece stays put; the count goes down.
Application
Application of like-denominator subtraction to whatever pair of fractions the next dive brings up, across 6 rounds.
Reasoning
Reasoning about why 4/7 minus 1/7 equals 3/7 — the parts haven’t changed size, only count, and that holds for subtraction the same way it holds for addition.
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Prasanna Devi
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Love for Math
"Our 4th grader loves math thanks to Rashmi Mam. Her patient, fun, and encouraging teaching has boosted confidence, focus, and test performance—making every session enjoyable."
SJ
Santhosh Jha
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Awesome Math Teacher
"Thanks to Abanti Mitra Mam. She's been a wonderful teacher for our 7th-grade daughter for 2.5 years. Patient, explains concepts well, adjusts timings, and gave extra sessions before exams."
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Jahnavi Vutharkar
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Shyam Deshmukh
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Exceptional Guidance
"Ms. Shalini Kumar is the best of the best—very experienced and always working hard with my daughter to help her achieve great results in math. We continue booking with her every year."
LH
Linet Haratunian
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Dedicated Math Mentor
"Ms SURANA has real enthusiasm and energy to teach. My kids improved their math skills drastically with her. Thanks Ms Priya."
ÜA
Ümit Aykut
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Motivation That Works
"Reena is an amazing teacher who builds motivation gently and effectively. Our son looks forward to every session. Cuemath has deepened his understanding and let him explore topics he loves."
J
Jen
🇺🇸
Caring, Clear Support
"As a parent, I feel valued and supported by Mrs. Puduru Sandeepa. She involves me, always communicates clearly, and creates a caring environment that improves my daughter's understanding."
E
Eliza
🇺🇸
Confidence in Math
"My daughter has made major academic improvements since joining Cuemath. She's more confident because Ms. Supriya teaches using her school textbooks. Enrolling her in Cuemath was a great decision!"
MO
Myra Olarte
🇺🇸
Math Support for ADHD
"I'm so grateful for the amazing support Ms. Mehak has given my son with ADHD. Her patience and creative teaching have built his confidence. He looks forward to math and enjoys learning!"
S
Shital
🇺🇸
Math Made Enjoyable
"Ms. Supriya has been teaching my daughters for 3 years. She tailors lessons patiently, builds confidence, and skills. My girls actually enjoy learning math with her, which says a lot!"
P
Payal
🇺🇸
Love for Math Lessons
"Our son looks forward to his math lessons with Ms. Sonal Kesal. She is incredibly patient, explains concepts clearly, keeps him engaged. He progressed to 5th grade math mid-4th grade."
R
Radhika
🇺🇸
Ahead in Math
"My daughter has been with Cuemath for 2+ years. With tutor Anjali and engaging worksheets, she's made tremendous progress and can confidently solve 2nd-grade math in 1st grade."
KC
Karpukkarasi Chandrasekar
🇺🇸
Math Skills Improved
"My son has been with Cuemath for 5 years, from 1st-6th grade. I've seen a huge improvement in his confidence and problem-solving skills. He now approaches math with excitement, not fear."
RS
Ravikumar Sidda
🇺🇸
Wonderful Math Teacher
"My 3rd-grade son has improved greatly, and his love for math puzzles has grown tremendously after joining Cuemath. Ms. Atluri Ratna's expertise and engaging teaching make math truly enjoyable."
PD
Prasanna Devi
🇺🇸
Love for Math
"Our 4th grader loves math thanks to Rashmi Mam. Her patient, fun, and encouraging teaching has boosted confidence, focus, and test performance—making every session enjoyable."
SJ
Santhosh Jha
🇺🇸
Awesome Math Teacher
"Thanks to Abanti Mitra Mam. She's been a wonderful teacher for our 7th-grade daughter for 2.5 years. Patient, explains concepts well, adjusts timings, and gave extra sessions before exams."
JV
Jahnavi Vutharkar
🇺🇸
Gaining Confidence
"My child in 7th grade has gained confidence in math reasoning with Cuemath teacher Payal Agrawal. She explains concepts clearly and tailors her teaching to my child."
RS
Rekha Silwal
🇺🇸
Math Feels Easy
"My son started Cuemath in 2nd grade and still loves it in 5th! Thanks to Ms. Vinita's creative, fun teaching, math feels easy and exciting. He looks forward to every Cuemath class!"
SD
Shyam Deshmukh
🇺🇸
Exceptional Guidance
"Ms. Shalini Kumar is the best of the best—very experienced and always working hard with my daughter to help her achieve great results in math. We continue booking with her every year."
LH
Linet Haratunian
🇺🇸
Dedicated Math Mentor
"Ms SURANA has real enthusiasm and energy to teach. My kids improved their math skills drastically with her. Thanks Ms Priya."
ÜA
Ümit Aykut
🇺🇸
Motivation That Works
"Reena is an amazing teacher who builds motivation gently and effectively. Our son looks forward to every session. Cuemath has deepened his understanding and let him explore topics he loves."
J
Jen
🇺🇸
Caring, Clear Support
"As a parent, I feel valued and supported by Mrs. Puduru Sandeepa. She involves me, always communicates clearly, and creates a caring environment that improves my daughter's understanding."
E
Eliza
🇺🇸
Confidence in Math
"My daughter has made major academic improvements since joining Cuemath. She's more confident because Ms. Supriya teaches using her school textbooks. Enrolling her in Cuemath was a great decision!"
MO
Myra Olarte
🇺🇸
Math Support for ADHD
"I'm so grateful for the amazing support Ms. Mehak has given my son with ADHD. Her patience and creative teaching have built his confidence. He looks forward to math and enjoys learning!"
S
Shital
🇺🇸
Math Made Enjoyable
"Ms. Supriya has been teaching my daughters for 3 years. She tailors lessons patiently, builds confidence, and skills. My girls actually enjoy learning math with her, which says a lot!"
P
Payal
🇺🇸
Love for Math Lessons
"Our son looks forward to his math lessons with Ms. Sonal Kesal. She is incredibly patient, explains concepts clearly, keeps him engaged. He progressed to 5th grade math mid-4th grade."
R
Radhika
🇺🇸
Ahead in Math
"My daughter has been with Cuemath for 2+ years. With tutor Anjali and engaging worksheets, she's made tremendous progress and can confidently solve 2nd-grade math in 1st grade."
KC
Karpukkarasi Chandrasekar
🇺🇸
Math Skills Improved
"My son has been with Cuemath for 5 years, from 1st-6th grade. I've seen a huge improvement in his confidence and problem-solving skills. He now approaches math with excitement, not fear."
RS
Ravikumar Sidda
🇺🇸
Wonderful Math Teacher
"My 3rd-grade son has improved greatly, and his love for math puzzles has grown tremendously after joining Cuemath. Ms. Atluri Ratna's expertise and engaging teaching make math truly enjoyable."
PD
Prasanna Devi
🇺🇸
Love for Math
"Our 4th grader loves math thanks to Rashmi Mam. Her patient, fun, and encouraging teaching has boosted confidence, focus, and test performance—making every session enjoyable."
SJ
Santhosh Jha
🇺🇸
Awesome Math Teacher
"Thanks to Abanti Mitra Mam. She's been a wonderful teacher for our 7th-grade daughter for 2.5 years. Patient, explains concepts well, adjusts timings, and gave extra sessions before exams."
JV
Jahnavi Vutharkar
🇺🇸
Gaining Confidence
"My child in 7th grade has gained confidence in math reasoning with Cuemath teacher Payal Agrawal. She explains concepts clearly and tailors her teaching to my child."
RS
Rekha Silwal
🇺🇸
Math Feels Easy
"My son started Cuemath in 2nd grade and still loves it in 5th! Thanks to Ms. Vinita's creative, fun teaching, math feels easy and exciting. He looks forward to every Cuemath class!"
SD
Shyam Deshmukh
🇺🇸
We love solving doubts
What is subtracting fractions with like denominators?
Subtracting fractions with like denominators means taking the difference of fractions whose bottom number — the denominator — is the same. Because each fraction is already cut into the same-sized pieces, you only need to take away how many pieces are being subtracted. So 4/7 - 1/7 = 3/7: four pieces minus one piece equals three pieces, and each piece is still a seventh. The denominator doesn't change; only the numerator does. It's the same rule as adding like-denominator fractions, run in the other direction.
Why doesn’t the denominator change when we subtract fractions with the same denominator?
Because the denominator describes the size of each piece, not how many pieces you have. Taking pieces away doesn't change the size of any single piece — each one is still a seventh, or a tenth, or whatever the denominator names. Subtracting 1/7 from 4/7 means removing one seventh-sized piece from a group of four. You now have three pieces, but each piece is still a seventh. Subtracting the denominators would mean re-cutting the pizza into different-sized slices — which isn't what subtraction does. It's the same trap as addition, and the same fix applies: the denominator names the size, the numerator names the count, and only the count changes.
Does the game explain how to play?
Yes. The game opens with a short tutorial that introduces the diver, the shells, and the way pearls are released when the right shell is picked. From the second round onwards, students play independently. This means Grade 4 students can play without an adult walking them through the rules first.
How long does it take to play?
A full playthrough of all 6 rounds takes about 5 minutes. Each round is one fraction-subtraction problem and one shell click, so the pace is set by how long the student wants to think before picking. There's no time pressure — the diver waits, and a wrong shell simply shuts closed without ending the round.
Is the game free? Will it stay free?
Yes. Subtract to Collect the Pearls is free to play now and will remain free. It's part of Cuemath Playground — a library of games that Cuemath tutors use with paying students, made freely available as part of Cuemath's mission to make every child MathFit. No signups, no paywalls, no hidden tiers.
Are there ads or distractions in the game?
No. The game has no third-party ads, no pop-ups, no promotional interruptions, no chat, and no user-generated content. A child can play any round from start to finish with nothing on screen except the game itself.
What should my child learn after this?
Once a child can confidently subtract fractions with the same denominator, the natural next steps are subtracting fractions with unlike denominators (which uses the same common-denominator move as unlike-denominator addition) and adding or subtracting mixed numbers (which combines whole-number arithmetic with the fraction work). Both are Grade 4–5 topics covered in other Cuemath Playground games and in the full Grade 4 math curriculum.
How is this different from Math Gym in the Cuemath app?
This game lives on Cuemath's website as part of Cuemath Playground — a free, browser-based library of concept-specific games tied to grade-level curriculum (this one is built around Grade 4 fraction operations). Math Gym is a separate section inside the Cuemath app, with daily strategy games, logic puzzles, and mental-math challenges — built around general mathematical fitness rather than a specific topic. Both belong to the MathFit journey, but they serve different purposes: Playground works through curriculum concepts; Math Gym builds daily practice across strategy, logic, and mental math. You don't need the app to play this game.
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