You should bear in mind that when distributing musical instruments, it is of course very tempting for children (and adults!) to play these instruments as they are being distributed. A teacher could capitalise on this and set a specific task for children to do during this time, for example to practise a passage of music that is related to the task, or to explore their instrument creatively (e.g. by giving them the instruction that they should find the longest/shortest/most unusual sound their instrument can make).