To view the gradebook in full screen just tap on Full screen button (top right) shown below
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Faster way to do it:
Double tap (with two fingers) on the gradebook, you can switch between the two modes easily
Double tap (with two fingers) on the gradebook, you can switch between the two modes easily
In order to be able to see more students per page you can change the students row's height with a tap on the Options button top right as shown below.