In Canvas you can set a material to "close" from and until certain dates by setting up the "Available from" and "Until" dates. Sometimes when you do this you need to unlock a material for a specific group of students.
Video Walk-Through:
https://player.vimeo.com/video/450229599
Step-by-Step Guide with Screenshots:
1) Access the material's settings.
Click on the desired material.
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Click on Edit from within the materials page in Canvas.
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2) Add another assign box.
Scroll down in the material settings until you see the Assign to box.
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Click on +Add at the bottom of the box to create another Assign to box.
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