The game differs from its predecessor by an increase in the size of the play area (including a neighbouring girls' school) and a number of gameplay changes.

The girls' school incorporates its own new characters including undistinguished girls with hockey sticks, Hayley (girlfriend of the main character Eric) and Miss Take (the headmistress). Only at break time and lunch times are the girls allowed to mingle with the boys, in the central grassy playground, separated at other times by a high gate. The opening and closing of the gate is controlled by the school caretaker Albert, a new character to the game. It is also possible for Eric to sneak over the gate into the girls' school during lesson times, either using the bicycle (after completing the challenge of finding its lock's combination and then performing a tricky manoeuvre on it), by watering the flower beside the gate and then jumping on it, or by kissing Hayley through the gate. When the girls and boys are allowed to mingle and when Eric gains access to the girls' school, he can kiss Hayley, who will then agree to do 1000 of his lines for him. This reduction method can be used up to six times before Hayley refuses to help Eric any more.

Elements added in Back to Skool include stink bombs (used to trigger the opening of windows), water pistols, mice that can be released in the girls' school causing widespread panic, and sherry (which can be squirted into cups and used to "intoxicate" teachers by splashing it on them with correct timing).