Correct technique:

With the tongues swept out of the way, and the tip of the laryngoscope blade in the vallecula, you are now ready to elevate the mandible. This should provide an unobstructed view of the vocal cords, and room to pass the ET tube into the trachea.

Note correct technique:

The mandible is elevated by moving the handle in the direction it is pointing, at approximately a 45 degree angle. The handle should not be used as a lever, as this can result in dental injury.

Incorrect technique:

It is common for novices to pull back on the handle of the laryngoscope to facilitate visualization of the cords. This can result in significant injury to the teeth or lips.

DO NOT USE THE HANDLE AS A LEVER! Note that by pulling back on the handle, the rescuer in this video clip is coming in contact with the patient's teeth.