@AmyFolsom85
It seems strange (to me) that a district would lock the dates on a sandbox course. The teacher participation is often controlled by what term the course appears in. You might go into your sandbox course settings and look to see if you can change the term and/or start and end dates. Those are typically locked down for SIS created courses, but for manually created courses you might be able to change the term. If manually created, it might have been that you set the term yourself to match the final course and so you can just change it to the new term now. There may be a "default term" that has no dates -- that's what our institution uses for Sandbox courses.
If that doesn't work, you may ask your local Canvas admin to reset the dates for you or create a new sandbox.
You can create an account on the Canvas Free for Teachers platform, but since it's a different instance (and not everything, including New Quizzes, is not supported), you will have extra hurdles to jump through when trying to import the content into your real course. It's really best if your local Canvas admin helps.
