Comparison

Pearl Diver HD vs Stack Up

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Pearl Diver HD

Dive into the ocean depths to master the number line, including fractions and decimals, by collecting pearls. This game is designed by educators to align with Common Core standards for grades 3-8.

Highlights
  • Number line mastery
  • Fractions and decimals
  • Common Core standards alignment
  • Progress tracking
  • Educational game design
  • Pearl collection gameplay
Features
Read full description

Throw on your diving helmet, and head into the depths of the sea! Master the number line, including fractions and decimals, while gathering beautiful pearls. Will you find the elusive black pearl? • Ideal for elementary and middle school students, grades 3-8. Developed by mathematics educators, researchers, and game developers at the Learning Games Lab at New Mexico State University. Games developed by the Learning Games Lab undergo a rigorous instructional design process, extensive user testing, and input from learners, teachers, and researchers. Pearl Diver addresses Common Core standards relevant to the number line and properties of numbers, including: • Understanding numbers, ways of representing numbers, and number systems. • Understanding and representing commonly used fractions. • Understanding fractions as part of unit wholes and as locations on number lines. • Comparing and ordering fractions, and finding their approximate locations on the number line. For information about learning effectiveness, see the Math Snacks Research Summary: http://mathsnacks.com/research.html For information about the NMSU Learning Games Lab, visit http://learninggameslab.org. Developed as part of the "Math Snacks" initiative. Other free animations, activities, and games are available through the Math Snacks web site at http://mathsnacks.org. Math Snack materials were developed with support from the National Science Foundation (0918794). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Some materials were originally prototyped or discussed as part of a cooperative agreement from the U.S. Department of Education (U295A050004).

About

Stack Up

This educational app helps children aged 2.5 and up learn to arrange items by width. It fosters visual perception and primary math skills through engaging, simple activities. Designed for young learners, it avoids distractions and offers progress tracking for educators.

Highlights
  • Arranging items by width
  • Develops visual perception
  • Teaches primary math concepts
  • Progress tracking for educators
  • Safe for children
  • Simple and intuitive design
Features
Read full description

- Full version. - No in-app purchases. - No ads. - Safe for kids. Welcome to “Stack Up”. This educational app is designed for children aged 2.5 and above. Here children can learn to arrange items bottom-up according to their width. It is fun, and it helps them develop visual perception skills, and primary math concepts. STEP BY STEP is a professional EdTech studio that focuses on developing educational apps for children aged 1 to 5 years old. During these critical years, children enter a new learning stage every few months. Our apps support and strengthen the development of crucial skills for each learning stage. This way we guide your children, step by step, throughout this entire age range. Our key values are perfection and simplicity. We believe that small details make a big difference, so we give great attention to every detail — both in content and design. Most importantly, we keep our apps simple — simple to understand and simple to use. While playing our games, children will engage in simple activities, such as matching, pairing, ordering, grouping, and sorting. This allows them to practice essential skills, such as: categorization, conceptualization, generalization, abstraction, memory, language, math, visual perception, fine motor, accuracy, attention, and focus. They will learn about shapes, colors, animals, fruit, vegetables, clothing, tools, vehicles, furniture, professions, toys, etc., — all while playing. The levels are generally arranged by difficulty. The first levels are usually quite simple — their main objective is to teach players critical thinking and problem solving. However, the exercises become increasingly challenging as the child advances within the game. Our applications avoid distractions such as popups, unnecessary animation, and noisy feedback. We keep our applications safe for children — no advertisements, no unsafe links to external content, no popups, etc. Furthermore, our experience indicates that our apps can be very helpful for children with special-needs¹, and that they can function as useful tools in both speech-language therapy² and in occupational therapy³. In addition, our apps have been found useful for adults with disabilities or dementia⁴. For this reason, we added two important features: the first one was designed for teachers, therapists, and speech pathologists, which allows them to track the progress of their students; the second feature makes our apps also accessible for users with disabilities, and on this matter we would like to thank the Technology Consulting Center at “Beit Issie Shapiro”⁵ for their professional guidance and consultation regarding accessibility. ________ ¹ Special needs - Learning difficulties due to learning disabilities, communication disabilities, emotional or behavioural disorders, physical disabilities and/or developmental disabilities, which may be caused by Autism (Autistic Spectrum Disorders), Down Syndrome, Dyslexia, Tourette Syndrome, etc. ² Speech-language therapy - Treatment of communication disorders by speech-language pathologists (SLP). ³ Occupational therapy (OT) - Treatment meant to develop, recover, or maintain daily living and work skills for people with a physical, mental or developmental condition. ⁴ Dementia -  A condition caused by brain injury (BI), brain damage or brain diseases, such as Alzheimer’s, Lewy bodies (DLB), Vascular dementia, etc. ⁵ "Beit Issie Shapiro" is a leading non-profit organization that develops therapies for people with disabilities, and also acts as a ‘Special Consultant’ to the United Nations.

Screenshots

Pearl Diver HD4 screens

Verdict

The call

The clearest difference is rating: Stack Up at 5.0 against Pearl Diver HD's 1.5. Stack Up also leads on update cadence (every 2 months vs every 20 months) and review sentiment (100% vs 71%). On price, ads, in-app purchases and monetization model there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Stack Up holds the better App Store score, 5.0 against 1.5. Both are backed by a comparable volume of ratings — 2 and 6 respectively. Written reviews point the same way: 71% of Pearl Diver HD's written reviews are positive against 100% of Stack Up's.

UpkeepUpdate frequency

Pearl Diver HD ships an update every 20 months, Stack Up every 2 months. The most recent releases landed on November 1, 2026 and November 6, 2026 respectively.

Scorecard5 real differences · 5 level
Pearl Diver HD versus Stack Up: the parameters behind the verdict, then further details
ParameterPearl Diver HDStack Up
PriceFreeFree
Rating1.5 (2 ratings)5.0 (6 ratings) — better
Positive reviews71.4% of reviews100.0% of reviews — better
Number of ratings26 — better
Update frequencyEvery 20 monthsEvery 2 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
DevicesiPhone, iPad — betteriPad
Requires iOS17.67.0 — better
Further details — not scored
Size28 MB65 MB
Age rating4+4+
DeveloperNew Mexico State University Board of RegentsSTEP BY STEP

Customer experience

Pearl Diver HD

All ratings2 ratings
Positive0.0%
Neutral0.0%
Negative100.0%
Written reviews7 reviews
Positive71.4%
Neutral0.0%
Negative28.6%

Stack Up

All ratings6 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews3 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Pearl Diver HD

No in-app purchases

None

Stack Up

No in-app purchases

Questions

Is Pearl Diver HD free?
Pearl Diver HD is free to download, with no in-app purchases.
Is Stack Up free?
Stack Up is free to download, with no in-app purchases.
Which has better reviews, Pearl Diver HD or Stack Up?
Stack Up is rated higher. Pearl Diver HD averages 1.5 out of 5 from 2 ratings, while Stack Up averages 5.0 from 6 ratings.
Do Pearl Diver HD or Stack Up have ads?
Neither Pearl Diver HD nor Stack Up shows ads.
Which is updated more often, Pearl Diver HD or Stack Up?
Pearl Diver HD ships an update every 20 months, and Stack Up every 2 months. Most recently, Pearl Diver HD was updated on November 1, 2026 and Stack Up on November 6, 2026.

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