From our district's website:
Target Student/Teacher Ratio
20:1 first, second & third grade/acceptable range 18-24
24:1 fourth grade/acceptable range 22-28
28:1 fifth & sixth/acceptable range 26-32
*150 students per day/per teacher
*Class size varies depending upon subject

For the gt classes, the class size used to be smaller. Now, to avoid misguided charges of elitism and avoid drawing unwanted attention from the budget hounds, the gt class sizes seem be in the same range as the traditional classes.