slatour Hi, MoodleBox's DHCP server is active only on its wireless interface, not on its ethernet interface. In fact, MoodleBox is a DHCP client on the ethernet side. So, if you connect the MoodleBox to your school's (cable) LAN, it will get the IP configuration of its ethernet interface from the DHCP server of the school. So, the answer is Yes. You don't have to do anything!
There is even more: If the school's DHCP server also assigns a default route (Internet gateway) to its clients, your MoodleBox will have Internet access and so do the wi-fi clients connected to it. If you don't want the pupils getting lost in the Internet, just pull the cable! ;-)