JXCirrus Maths for Mac is a program that lets you set up sets of exercises for your kids to help them practice their math skills. You can tailor the quizzes to their ability level, and the program keeps track of their time for them, so they can compete against themselves and measure their progress.
This app has an intuitive interface, letting you set up different sets of exercises quickly. When you're adding an exercise, you'll first select either Addition, Subtraction, Multiplication, or Division. Then determine how many problems you'd like, which numbers to use, and whether you want the equations to appear in numerical order or randomly. You can also select whether you'd like individual sets of problems to show up for each session, once a day, or once a week. Add as many sets of exercises as you want, and then let your kids test themselves. When they start a session, they can pick the set of problems they want to try, and then a list of equations will show up in a new screen. As they type their answer into the box at the end of the equation, the cursor will automatically move to the next box. The program times how long they take for each equation and for the whole set in total, so they can try and beat their best scores and see how they are improving over time.
There is a full Help document available for this program, although the straightforward interface makes finding most features a snap. This app is free, and it runs smoothly, making it a good choice if you want your kids to have a fun way to practice math problems on a regular basis.