Each service has different limits associated with it. Please see below:

 

Mail: Each user has 25 GB of storage.

 

 

Drive: With the implementation of Google Drive, all users will have 5 GB of storage.   

 

 

Sites: Embedded documents, including Google Documents, don't count against the Sites storage quota. However, items added as an attachment or to your file cabinet do count against your quota.

• Site quota: N/A (quota is tracked at the Cedarburg domain level)
• Quota per domain: 100GB
• Max attachment size: 20MB
• Sites per domain: unlimited
• Pages per site: no set limit

 

Video: Google Video for education offers 10GB free of charge to Google Apps for Education customers. It's not currently possible to purchase additional space.