Dealing with stress is an advanced skill that teaches children how to identify stress, finding strategies to feel less stressed and take actions towards it. Techniques such as deep breathing, muscle relaxation, and physical exercise are ways children can manage stress.
Your have a math test tomorrow and you are stressed about how you are going to do.
Take a few deep breaths to relax. You could also express your feelings by telling your mum or dad how you feel. You could also act on those feelings and decide to revise a little more before going to bed for peace of mind.