Checking, fixing and editing proofs

What should I do if the system gets stuck or thinks for a long time when I ask for a hint or a check?

The system saves your solution all the time, not only when you submit. If it gets stuck, you can refresh the page and ask for the check or hint again — your work is not deleted.

Why doesn't the system accept my proof?

When your proof is checked you get detailed feedback on every step; go through it step by step and understand the mistakes. Sometimes one mistake carries over, and once you fix the first mistake the feedback on the later steps no longer applies. If that doesn't help, you can ask for a hint instead of a check.

What should I do if I found a mistake in how my proof was checked?

Whenever you get feedback from the system, the link Found an error? Let us know appears for reporting a mistake in the checking. Anyone can report a mistake, but we recommend that students report only after their teacher has confirmed that it really is a mistake.

How do I add a step to the proof?

Every step in the proof has a menu (⋮) with various editing actions, including Insert step above and Insert step below. Also, when you hover over the line between two steps, a small + appears. Clicking it adds a step.

How do I fix a proof?

After the check, click the button in the feedback (for example Fix the proof); you can then edit the proof and submit again. There is no limit on the number of attempts, but it's worth understanding the mistakes before trying again — then 2–3 attempts per item are usually enough.