ice breaker to practice observation skills
Ask everyone to team up with a partner (someone they haven't worked with yet, who has the same birth month, etc.) Ask them to introduce themselves then stand back-to-back. Once they are all back-to-back, ask each person to change 5 things about their appearance (including one which is silly). Once both partners are ready, have them turn around and try to guess the 5 things that have been changed.
Now we know who the sesnilbe one is here. Great post!