Instructions
Start "Call of Duty: Black Ops" and select "Zombies" from the main menu. Choose the desired map, such as "Kino der Toten" or "Five," and wait for your character to spawn in the map.
Scope out the area you were dropped in as quickly as possible. Take note of the placement and quantity of boarded up windows as this is where zombies get in. Also take note of extra weapons and doors.
Pick up a secondary weapon and begin killing the zombies as they walk up to the windows. Zombies will eventually break through the boards in the windows. To repair the boards, walk up to the windows and hold the "Action" button on the controller.
Press the right stick on your controller down to slash at the zombies with your knife. In rounds 1 through 3 this technique is very efficient.
Walk around the room to bunch the zombies up into a group if you aren't able to keep them outside the windows. Once they are bunched up, press the right bumper on your controller to throw grenades, and shoot your weapon directly into the group to kill them off. Following these techniques will get you through level three without difficulty.