In the able system, learners study the same problem until they can completely solve it on their own without any help from teacher. If a learner get a problem wrong just because a little time has passed, even though the learner got it right before, it means that there exists some problem in learning. able records and analyzes all relevant information, such as the date the learner solved the problem, the time it took to solve the problem, the input answers, and study location. We look at the solution process to see how we approached and solved the problem. In this way, we analyze which stage had the most trouble. We take a closer look at the right questions as well as the wrong ones. Because learning is not completely finished just because the learner got the answer right. It's more important to know exactly what the learner needs to learn through that problem and to learn. This is the direction of ‘learning history management’ that we pursue.