What materials will students use in order to succeed in their assessment of each weekly objective?

Your open course can include:

Content that you created yourself that has an open license on it; and
Content that someone else created that has an open license on it.

What do you already have?

Before you start searching for open content, inventory what you already have (and add it to your course layout spreadsheet if you're using one). This will narrow the scope of your search if you already have some of what your students will need.

In some cases, you'll just need to make minor revisions to existing content. Examples:

You created the course content and just need to add an open license (step-by-step instructions to openly licensing your work here)
You used open content and just need to add an attribution (step-by-step instructions to attributing open content here)

A medium-length scenario is if you used content that seems like the author wants to share but doesn't have an open license. If this is the case, it's worth contacting the author (or copyright holder) to find out whether they're willing to add an open license to their work or give you permission to use it in your openly licensed course.

What do you still need?

Any scaffolding that doesn't have content associated with it is what you still need to find or create. This module covers some basic OER search strategies. If you're falling down a search rabbit hole, STOP and ask a librarian. It takes a ton of time to design and teach a course, so let an expert save you some time on search.

The nice thing about having permission to reuse open content is that you don't have to reinvent the wheel. If you find something that's perfect, go ahead and reuse it. If you find something that's pretty good but doesn't quite meet the need, go ahead and revise it.

If you don't find anything that meets your need, then you'll have to create it yourself. A librarian can help you double-check that it's not already out there.