After an assessment, there are three views of the same data, and they answer different questions.
Getting there
Open the classroom, go to Assignments, click the assignment and then the lesson.
Students: how did each person do
One row per student with their total. Click one to read their answers and the feedback. Bulk actions across the top cover CSV export, resubmission, marking as completed and returning work.
Blocks: how did the class do on each question
One row per question, with the average mark. Click one to see everybody's answer to it. This is the view that finds a misconception.
Insights: what should I reteach
The Insights tab pulls out the themes across the class, so you do not have to infer them from thirty scripts.
For usage across the whole school rather than one assessment, use Insights in the sidebar. See Organisation Level Insights.