As per my experience with the stress a child goes through just before and after finishing with a test or exam, I have learnt to suggest to them that they spend their first 5-7 mins reading the questions, then do what they know confidently and move on to the tough ones in the last. This will help them not loose marks on what they knew. Most children spend their time first trying to solve the tough questions leading to them not having time for the questions they knew. In the end, always go through what you have written, the silliest of mistakes corrected can save you, your confidence and ofcourse marks. Most children ive seen dont follow this and tend to stress out a lot! Good Luck kiddos!