Website review by Emily Pohlonski, Common Sense Education | Updated July 2017

Fog Stone Isle

Fun virtual world builds deep understanding of fractions

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Based on 2 reviews
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Subjects & Skills
Math, Critical Thinking

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Pros: Carefully crafted games ensure long-term retention and conceptual understanding of fractions.

Cons: Each time students begin the game, plan on several minutes for it to load.

Bottom Line: A 3D world that uses adaptive computer manipulatives and multiple representations to help students retain important fractions concepts.

Teachers can use Fog Stone Isle to track both individual and class progress on key fractions ideas. This includes concepts that have been mastered, problems that have been solved, and procedural fluency for each child. Fog Stone Isle is best used as a routine spread out over the year; regular, spaced practice will ensure that students retain these ideas long term. Consider using Fog Stone Isle as part of your assigned summer learning program to prevent learning loss. Remind students to keep up their regular, spaced-out practice routine in the summer instead of simply cramming in a bunch of sessions at the end. 

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Fog Stone Isle is a site -- and app -- that uses brain-based research to help kids build crucial fractions concepts. With the guidance of a character named Cyril, students engage in playing video games. In an effort to keep the Gruffins safe from monsters, kids simultaneously build structures in their virtual world and encounter important fraction concepts. By properly adding fractions with like denominators, they can add bricks to the walls of their buildings. Kids learn about multiplying and comparing fractions as they build farms to feed their villagers.

Choice is key in the Fog Stone Isle world, as students decide where to build their fence for their Wild Rollerdillos or if they'd rather spend time building more farms. With each activity, kids learn different concepts, from fraction equivalence to lowest common denominator. The game is adaptive, adjusting to the student's math skills along with the student's memory and executive functioning ability.

Fog Stone Isle has found a way to help kids retain crucial fractions concepts. Because it's a fun video game, kids will come back regularly. Similar to Fruity Fractions, it uses multiple representations to get at the heart of a concept instead of simply having kids memorize rules. Fog Stone Isle adds the virtual world component that kids find addictive. At first glance, one 10-year-old exclaimed, "Ooh, this is just like Minecraft," and immediately wanted to play.  

Farming is surprisingly the most compelling component to Fog Stone Isle. Kids multiply fractions to determine which section of the plot gets watered. With an exciting sense of urgency, kids compare fractions to decimals to determine if they have enough water left to take out the weeds. The ever-changing grid on the farm plot lights up to give an additional visual representation. This is incredibly powerful in helping kids truly understand what it means to multiply fractions. 

Overall Rating


Kids will rave about the bizarrely fun games that continue to challenge. Students are empowered to create their own virtual Fog Stone Isle world.


Not all kids have the same level of working memory and executive function; Fog Stone Isle tracks this information and tailors tasks for each student. 


A sketch pad tool provides both text and visual cues to support kids. When adding with a common denominator, fractions are represented as bricks and placed on a number line, providing two different representations.

Common Sense reviewer
Emily Pohlonski Classroom teacher

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Featured review by
Kristi F. , Classroom teacher
Classroom teacher
Cedar Grove Elementary School
San Jose, United States
Excellent for teaching fractions!
I love this game. I like the conceptual models. Fraction multiplication is shown through visual representations and decimal representations. The system is easy to use. For teachers, it is easy to see the development of skills for each operation, and identify students that need additional support.
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