How many courses are offered by the Computer Info. Systems department?
SELECT count(*) FROM department AS T1 JOIN course AS T2 ON T1.dept_code  =  T2.dept_code WHERE dept_name  =  "Computer Info. Systems"
number of courses offered by a department refers to COUNT(*) of course entries; department name filtering refers to WHERE dept_name = 'Department Name'; joining tables department and course refers to JOIN on department code.