1) PageRank is figured per PAGE not per SITE
2) PageRank is Google’s measure of the AUTHORITATIVENESS of the page
3) To protect their market, Google displays PAGERANK that is 3-5 months old.

So, with the above information, your new site has a PageRank of 0 because it was not in existence 3-5 months ago. To increase the PageRank, you will want to seek links to your website from trusted places. Since you have an educational themed site, links from schools (.edu) would be a huge benefit.

Also, Google updates the PageRank on the toolbar about once a quarter. They just did an update, so the next one will be in about three months.