Shake thermometer so that the mercury falls below 97 degrees rectal (for kids 3 and under): Put petroleum jelly on the silver tip. Have the child lie on his stomach and gently slide the thermometer about half an inch into his rectum; hold it there for about two minutes. Oral (for children over 3): Insert the tip under the child's tongue and have him hold it there for two to three minutes without biting down. Axillary or underarm (any age): Tuck the tip into the child's armpit, then press his arm against his body for four to five minutes

A rectal thermometer is the most accurate way to measure a temperature; an oral thermometer is the next best bethod.

Rectal thermometers are awkward to use with a squirming child. And many children will not hold an oral thermometer under their tongue long enough to provide a reading; younger children could accidently bite off the tip. Some doctors do not recommend using the armpit method, because the reading may be affected by air exposure.

Place thermometer in the mouth, rectum or armpit, as with a mercury thermometer, and wait until it beeps.

Easy to read and highly accurate.

Batteries could expire at a crucial time. If dropped, could become less accurate

Tug lightly on the child's ear to straighten out the ear canal. Insert the thermometer and hold the button down for two seconds