Just playing a math facts game won’t build math fact fluency
There are a lot of apps out there that look like they would help your child learn math fact fluency. If they have to answer math facts, won’t that work? Not really. Just playing a game that asks you to answer facts won’t help you learn new facts. In fact, most apps for practicing facts are discouraging to students who don’t know their facts well. Why? Because most of the people designing the app don’t have any experience teaching. A teacher, like the creator of the Rocket Math App, is trained to effectively teach new math facts (or any facts) to a student and knows an effective math app from an ineffective one.
3 essential features of an effective math fact app
There are plenty of ineffective math apps. Some apps don’t give the answers when a student doesn’t know them. Some apps just fill in the answer for the student and then move on. When the student doesn’t know the answer, the app has to teach it. To teach math fact fluency, the app has to do these three things:

The app has to tell the problem and the answer to the student.

It has to ask the student to give the correct answer to the problem.

It has to ask the problem again after a short delay to see if the student can remember the answer.
Without doing these three things there’s no way the app is going to be able to teach a new fact to the student.
An effective math app will only teach a few math facts at a time
Nobody can learn a bunch of new and similar things all at the same time. A person can only learn two, three, or four facts at a time. You cannot expect to learn more.* That’s enough for one session. The student has to practice those facts a lot of times to commit them to memory. Once or twice is not enough. It also won’t help to practice the same fact over and over. Proper math fact fluency practice intermingles new math facts along with facts the learner has already memorized. However, no more than two to four facts should be introduced at a time. If a student has to answer a lot of random untaught math facts, you will have a very frustrated learner.
Practice must focus on building math fact fluency
Some students learn to solve addition problems by counting on their fingers. That’s a good beginner strategy, but students need to get past that stage. They need to be able to simply and quickly recall the answers to math facts. An app is good for developing recall. But the app has to ask students to answer the facts quickly, faster than they can count on their fingers. The app has to distinguish when a student is recalling the fact (which is quick) from figuring out the fact (which is slow). Second, the app must repeatedly ask the learned facts in a random order, so students are recalling. But the app should not throw in new facts until all the facts are mastered and can be answered quickly.
Introduce new facts only when old facts are mastered
The trick to effectively teaching math facts is to introduce new math facts at an appropriate pace. If you wait too long to introduce math facts, it gets boring and wastes time. If you go too fast, students become confused. Before introducing new facts, students need to master everything you’ve given them. An effective app will test whether students have mastered the current batch of math facts before introducing more facts. And it will also introduce math facts at a pace based on student mastery. That’s the final piece of the puzzle to ensure students learn math facts from an app.
*Rocket Math App focuses on two facts and their reverses at a time, such as 3+4=7, 4+3=7, 3+5=8 and 5+3=8.