Get a volunteer to look at your school homepage and another schools homepage. Ask them to do a task, like find the music teachers email or the principal's phone number that you KNOW can be accomplished.
Time them on how long it takes them to complete the task on each website. Count how many clicks it took them to complete their task for each website. Talk to them, and ask them to compare the two websites.
Write their response, time to task completion, clicks to task completion, and your summary thoughts in this discussion.
Do you see anything that your school homepage does well, or needs to improve on? Feel free to comment in this usability discussion forum.