Ideas
Sometimes students accidentally click the stop button a second or two after they start their recordings. This can become frustrating b/c then they are locked out and I have to go in during an assessment. One possible solution is to require students to have a minimum recording time and during that time that the teacher sets, the students the submit button is greyed out so that they are forced to talk. This may alleviate some of the headaches students cause teachers to have while administering tests. It also helps push the students to fill the required time.
So essentially there would need to be a min. amount of recording time and then another option to either stop the recording at that point or allow for students to keep speaking. For example: you must speak for 20 seconds but you can go up to 1 min. This encourages students to push themselves.
