Once you've assigned Missions to students, you can see how they've progress in the Missions Reports!
First, head to the Reports tab and click the View button for the mission you want to check on.
This page has a lot of data, so let's break it down into the different sections. The first section shows the individual results of each student. By default, the names begin anonymized but can revealed by clicked the eyeball icon. You can see the results of each question, the percentage of the mission that's been complete, how they fared on their first attempt and best attempt, and then finally the number of questions they went through total. As well, green checkmarks are for when they answer correctly on the first attempt, whereas light blue checkmarks are for best attempts.
You can also check any of the checkmarks or Xs to see how they answered on that particular question (both on their first and best attempt) and will also show any uploaded solutions for that question.
Below this, you can see the answering percentage for each question.
And finally below you'll see a detailed aggregate breakdown of how each question was answered. You can toggle between the first and best attempts with the switch at the top.