With respect to opening and closing of assessments, there are 2 options when assigning to students:
1. At a specific date and time: the students will have access to the assessment between the open date and the close date.
2. Open manually: This option will allow teachers to assign the assessment ahead of time and open the assignment manually for students when they are ready to take it. This was your 1st block can only take the assessment when you open it for 1st block.
Select "Open Manually in Class" in the drop down to the right of the start date.
Teachers have the option to pause an assessment at any point of time. This is handy if the teachers only want the students to work on an assignment during a specific window(ie. only in class and not at home)
You can open a paused assessment by then clicking on the Open button. The Open button replaced the Pause button when you pause and assessment.