Way one they can occasionally ask how the child is feeling but don't force them to answer.
Way two if they child is moping around sad just ask them if they are alright and give them a hug then back slowly back away giving them a moment to say anything that they want to say and if they don't want to just leave them alone.
Way three if the child is angry give them a minute to leave the room and calm down then calmly ask them what the problem is.
I know thats only three im sorry i just can't think of another one i hope everything goes good and im sorry if these didnt help i wish you the best luck with whatever your doing.