The fact that you have the jps named with the student ID is what is going to make this easy for you.
First make sure they are all in the same folder.
You are going to have to write a script to do this for you. But once you write it, the script will do all the work.
Basically, here is the script you need:
Go To Layout [Layout with students on them]
show all records
set variable[$path;value=PATH TO FILE WITHOUTFILENAME]
For help setting the correct path to where your photos are, add an INSERT PICTURE script step and clic specify source file, navigate to the folder where your photos are and pick any one. Copy and Paste from the beginning until the last "/". Paste that into the value of the $path variable.
Go to Record Request [First]
Go To Field PHOTO
Insert Picture (you can use the one you already added) Clic specify source file and type $photo in the dialog box and hit ok.
Go To Record Request [NEXT, exit after LAST]
Commit Record Request
AND YOU ARE DONE.
Here is a description of what the script is going to do:
Go to the layout where I want to add the photos. Show all the records, because I want to add photos to all. All the photos are in the same folder, but they each have a different name, so store the path to the folder in $path. Go to the first record to make sure I don't miss any. Start a Loop because I'm going to do the same thing for a whole lot of records. Set $photo to combine the path to the folder, the STUDENTID that is the file name and the extension of the file name so Filemaker know where to get it from without me importing one by one. Go to the photo field because that is where I'm going to put the photo in, Insert the photo that is at $photo on my computer. Go to the next record, and when you finish with the last one, get out of the loop. And finally commit the record...
Hope this helps...
You might also look in to Import Records | Folder option
This is an option you can use to import an entire folder of jpegs in one go. You can most easily use this tool to import the photos into a related table and import the file name into another field in this table at the same time. At that point, using the file name to link to your original table should be a fairly simple calculation field that extracts the student ID from the file name.