First, the child has to think about why she/he feels left out and whether this is accurate or not. Then, the child should think about what action he/she can do to join the group and what to do if the group says that they don’t want to play with him/her.
Your friends tell you that there isn’t enough room for you to help with the puzzle.
Identity how you feel, then look at how to deal with the rejection. Possibly take deep breath, or walk away. Take things into perspective and find something else to do. It’s ok to feel rejected, it happens.