The sentence given basically means:
"After studying in school and playing tennis by afternoon, the kids/guys are..."
You could end with lot different things, like saying they were tired or they went to eat. Here i'll provide some examples, for you to give an idea on what to write.
Examples:
"...agotados/cansados." (Which means tired)
"...con sueño." (sleepy / feel tired)
"...estudiando en casa." (Studying in their house)
For me the best one is "estudiando en casa"