I have created two custom modules:

Module 1 - School District - a list of schools districts

Module 2 - Schools - a list of schools

In Module 1 there is a District ID for each district.

In Module 2 there is a district ID field that says which District a school belongs

Here is my challenge. In the Contacts Module, I want to allow users to select the district that the contact belongs to and then when they select which school the contact belongs to, I want on Schools that belong to that district to appear.

Any ideas how I would achieve that?