Hi @heather_edwards -
Currently, there isn't an easy way to determine who has accessed a specific page. However, if you use modules and use requirements (How do I add requirements to a module?), you can make sure that a student access specific content before opening an assignment.
To take this idea further you could use an API token and https://community.canvaslms.com/docs/DOC-5499-automated-progress-report-of-students-in-modules to get more in-depth information which is sortable on a spreadsheet.
There is not any way directly from within the web interface using the core Canvas product.
You can determine that from Canvas Data, but that's generally not available to faculty and it's delayed by at least 18 hours -- often more, so it's not real-time.
The closest thing I know of is Obtaining and using Access Report data for an entire course, which will gather all of the access reports for an entire class and then you can open it spreadsheet and filter or make a pivot table to view all kinds of views and participation data for the entire course.
Blackboard had an option to view how many times and which students had accessed a given file. I wish Canvas could do this. It would be very helpful because then we could see which supplemental resources are most used.