Happy Numbers is a nice online site, iPad compatible, used to allow students practice opportunities towards mastering the traditional addition and subtraction algorithms.
While working on problems, students are guided through the process of completing the algorithm. Each step must be completed correctly without an error to get the problem "correct". Once the student has answered 10 questions complete "correct" they have completed the level for the day.
Data is stored online showing progress of students throughout levels that are available to them.
As a teacher you create your free account. Then create a class. After the class type in your students name. Happy Numbers will assign a class number to your class, and a password for each student. You can change passwords if you would like.
For students to login, they type in the class number, click their name, type their password, and proceed onto their practice for the day.
This site is quick to set up for you and your class, saves data about your students daily practice, and provide students practice opportunities while mastering the standard addition and subtraction algorithm.