...
Record Granular Data: Your custom web activity will be responsible for a legitimate academic exercise, and it should keep records of users’ interactions, responses, and submissions. By doing so, your custom web activity will help ensure the integrity of students’ coursework.
Check if the Launch Token has Previously Been Used: When configuring a custom web activity in Terracotta, there is a checkbox: Tool allows students to view past submissions. If this box is checked, Terracotta will assume that the tool is able to display a past submission to a student. In this situation, if the external webpage receives a launch token that has previously been used, this indicates that a student is attempting to review their responses from a past submission. Check if the launch token has previously been used, and that the anonymous_id and assignment_id of the current launch matches the anonymous_id and assignment_id of the past submission associated with the launch_token. If so, the external page should display the data from the past submission associated with the provided launch token, with no interactivity.
NOTE: There is one a reserved launch_token: "0000000-0000-4000-a000B000-000000000000". This launch token is issued by Terracotta when previewing external integrations a custom web activity.
Communicate When There are Limited Remaining Attempts: When the teacher has placed restrictions on the number of attempts that a student may submit in response to an assignment, it may be helpful for the custom web activity to communicate this to the student (e.g., if there is only 1 attempt remaining). If there are unlimited attempts available to the student, remaining_attempts = u. A custom web activity will never need to handle a situation where remaining_attempts = 0, because in this situation, Terracotta will not generate a launch_token and will not launch the student into an activity.
Respect Due Dates: Consider warning users when they are accessing the webpage after the due date. Submissions made after the due date will be delivered into Canvas, but will be flagged as late.
Score Calculation: The custom web activity is responsible for determining the student’s score on the activity, which should be returned to Terracotta as a URL parameter value with the name “score.”
...