Motion Math: Hungry Fish is designed for a wide grade range of kids, some of whom may have already learned the fundamentals of addition and subtraction. It’s excellent for practice but isn't a substitute for the conceptual understanding that comes from working with concrete materials -- use both practices in tandem.* *Hungry Fish will help kids memorize certain combinations of two or more numerals, and while computational fluency does allow for flexible methods of computing (i.e., without pencil and paper), it does assume that whatever method kids use is grounded in understanding.

In Motion Math: Hungry Fish, the title character wants to eat a number shown on its side; kids combine number bubbles to create the food it wants. To subtract, kids combine positive and negative numbers. It’s designed for a wide range of grade levels and with six games and 18 difficulty levels, so kids can use Motion Math: Hungry Fish for years of practice as their math skills grow. The app allows more than one player to register, so multiple kids can play without affecting other players' progress or scores. Levels of difficulty vary by speed and what the fish wants; in the easiest levels, kids simply match number bubbles. Leveling up depends on how fast the fish grows. In Caves games, a Mad Fish eats wrong answers and endangers the hungry fish. Rewards include points and options to customize your fish. To change the difficulty level, pause any game or visit the Options area. The pro version has two types of games for addition, subtraction, and negatives practice and 18 levels of difficulty. It’s based on Common Core standards for math in kindergarten through fourth grade.

**Full Disclosure: Motion Math and Common Sense Education share a funder; however, that relationship does not impact Common Sense Education's editorial independence and this learning rating.**

Kids learn addition and subtraction as they combine positive and negative number bubbles to create the number the fish wants to eat. The game makes smart use of touch-screen interactivity. The touch, drag, and combine actions are similar to how kids learn arithmetic with number cubes; here, they'll enjoy the immediate feedback they get from the number-bubble combos and the growing or shrinking fish. In short order, they learn which number combinations get results, and voila! They’re doing mental math.

A few functions help gauge kids' learning. Each game is timed so if the fish is not fed enough, he shrinks until he -- and the player -- no longer survives. But once kids learn how to make correct combinations, there are two ways to advance. If they're speedy about combining numbers and feeding the fish so it grows big pronto, they automatically win the level and advance to the next hardest one. If a player's pace allows the fish to survive the level but not grow really big, he's rewarded with lots of correct number bubbles to end the level.