You can pause an assessment by selecting the pause button at the top of the instruction screens before starting an activity. When you pause an assessment in this way the device will keep the data for the activities already completed and will resume from the next activity in the assessment. Note that an assessment can only be resumed on the same device that it was paused on.
If you need to stop an assessment as a matter of urgency in the middle of one of the LanguageScreen activities you can tap the exit button. This will delete the data for the current activity and will pause the assessment so that it can be resumed from the start of the activity that was interrupted. It should be very rare to need to exit an activity during an assessment. Try to only pause an assessment before starting an activity.
Once you have paused an assessment you can assess other children. You can return to the paused assessment, whenever the child is ready to continue. You can see paused assessments on Assess/Resume screen of the app. To resume a paused assessment, you will be prompted to scan the QR code again for that child and their assessment will begin where you paused it. Note that you can only resume a paused or interrupted assessment on the same device that the assessment was first attempted.