Once they master that, then teach them 6-9. Once you have the counting and the finger action down pat, you are ready to do Fingermath. To add, simply press the first number you want to add, then start adding fingers up to the amount of the second number you want to add. Press 5, count out 6 more fingers and you suddenly see a 1 on the left hand and a 1 on the right hand. But she could never tell you off the top of her head that 5 plus 6 makes 11, at least not yet.
Subtraction is just the reverse of addition.
When you raise fingers off the table, you do it in reverse order, baby finger first. My 3rd grader is still struggling with basic math facts such as 16 minus 7, but by using fingermath, he just has to read the answer off his fingers. This method has even worked well with mentally handicapped children and blind children. We are also using it to a certain degree for multiplication. By the time we are done, we read our fingers and discover that we have 48 on our fingers.