How to reference a cell in a different workbook using a drop down
 

I created a file where each worksheet represent a different week. The tabs
look the same, but the data within the tabs are different. I am trying to
create a summary worksheet so that the user can select the week from a drop
down menu and the summary will automatically populate for the selected week.
I have created the drop down menu which contains the names of all of the
worksheets, but I am having trouble figuring out how to refence a cell on the
worksheet that the user select from the drop down list.

For example, lets say cell B2 contains the name of the student that has
detention on Monday. I want the user to be able to select the week from the
drop down menu from a "summary" worksheet and have a cell on the summary page
to display that student's name.

Anyone have any ideas how to do this?

Thanks from a frustrated teacher trying to make a task easier for other
teachers :)