Drop-down Value List only works in a layout made from Value List table?

[Ben Hires]

A new database with multiple tables was created for me. There is a student table and a school table. Everything is related to the student via their student ID. I have a main layout created from the Table "Students." Only fields from the table "students" seem to allow for a drop-down value list using the values from the field. Because a field from "schools" in the main layout created from "Students" stays blank. I tested this hypothesis by creating a layout based in "schools" - same field - and created a drop-down box and it worked.

 

Can anyone help me create a working drop-down value list for a field from another table in a layout based in another field? Basically in one layout I would like to see the school where a particular student attends.

 

Thanks!