How do I disable routing in a wireless router?

I want my router to send a wireless signal without assigning ip addresses. I am in a school and have received two wireless routers to expand our wireless network. I want my machines to get their ip address from our main network not from the wireless routers. Can I turn these routers into just signal senders?|||Some routers have procedures to turn them into access points only, which essentially turns the routing/dhcp off. Google around, or give us the make and model.|||turn off the dhcp on the secondary routers.connect the main router to the others LAN port to LAN. not LAN port to WAN.