I would probably charge the admission fee but meals are already part of the childcare fee so either plan to take a picnic lunch for the kids from home or be prepared to pay for the cost of the food yourself. As far as gas goes I assume for that too you have a certain budget already set for the program. Remember that you will be claiming the fees, gas, etc. on your taxes minus what you charge the parents if that helps. If you are not prepared to absorb most of the cost of the trip then you may want to reconsider if the trip fits into the daycare program or not. If you are charging I would keep it under $10 max and more likely charge $5-7 at most and be prepared for as reggio said a family choosing to stay home with their child rather than pay the additional fee but since you are unable to provide care that day because you are not home you would need to reimburse them for the day since they did not sign on to have to pay extra fees for care.