A great tool is Wisesoft Password Control which allows you to just type in the username, it will display info about the account and give you the option to change the password, enable/disable the account and unlock the account.
It is ideal to make available to teachers for resetting the student passwords if you use the Delegate control option in AD Users and Computers for your student OU’s.

The other useful tool on the website is a pair of tools Bulk Password Control and Bulk Modify. These allow you to bulk reset the password for a large group of students, or modify the attributes for a large number of users. It can read these in from a CSV file, and match the CSV entires to either sAMaccountName or some other user attribute. You can also set the attribute based on their existing attributes.

After downloading it will ask you for a code that you can get with a free registration on their site.