how to find the number of tests received from different sources

I have four school categorized from 1 to 4, and they were all administered the same test, how do I find out how many tests each school completed? So i would get data such as:
School 1= 120 tests
school 2= 90 tests
How's your data organized? I guess you have a "school" variable with values 1-4. Each case is a test? Or there's a variable with a number of tests?