Word isn't really designed to do this, but a starting point for doing this
without VBA is the MS Knowledgebase article at

http://support.microsoft.com/kb/211303

Imaigine that instead of "City" you have  "Subject", instead of "Employee"
you have "Student", and instead of "Sales" you have "Grade".

However, you may of course have other stuff that affects the structure of
the report - e.g. grades for a particular period, or perhaps you need to
produce reports for each class or each year in turn. Things can get pretty
complicated quite quickly!

One problem is that the output of this type of merge is a single document
(it's because you have to use a Catalog/Directory type merge to do it). If
you need for example to e-mail each student with a grade report, youwould
then have to split that output into separate files and remember which one is
intended for each student.

Among other possible approaches are:
a. copy your data into Access and use Access reporting (or link to your
Excel data source). If you have Access, that's probably the best approach if
you need printed output
b. use Excel or Word VBA to "roll your own" merge that produces each report
and e-mails it.

I am also a teacher, and utilize Excel power to gather data, and mail merge
into a Word document to make individual reports.  I have even made
personalized lesson plans.  Enter your information into columns, Student
names in column A/B.  Set up form in Word using Mail merge Wizard.  Merge
wizard will show columns when you select "Items".  Try it out!