To check for a fever using a thermometer, follow these general steps depending on the type of thermometer:

1. Oral Thermometer (digital):
   • Clean the thermometer.
   • Place it under the tongue, as close to the center as possible.
   • Keep the mouth closed and hold the thermometer in place for about 20 seconds or until it beeps.
   • Read the temperature displayed. A reading of 100.4ºF (38ºC) or higher usually indicates a fever.
2. Rectal Thermometer (often for infants):
   • Apply lubricant to the tip.
   • Gently insert about half an inch to one inch into the rectum (depending on age).
   • Wait until it beeps or for about 3 minutes.
   • Read the temperature which tends to be more accurate for young children.
3. Ear Thermometer:
   • Place the thermometer's sensor gently in the ear canal.
   • Follow instructions to take the reading, usually it beeps in seconds.
   • This measures the eardrum temperature and is quick and easy.
4. Forehead Thermometer (temporal artery):
   • Swipe or place the sensor across the forehead as per instructions.
   • Read the temperature.
5. Armpit (axillary) Thermometer:
   • Place the thermometer in the armpit.
   • Hold the arm tight against the body until it beeps.
   • This method is less accurate and typically reads lower than oral.

Important tips:

• Avoid eating or drinking 15-30 minutes before oral temperature measurement.
• Always clean and disinfect the thermometer before and after use.
• Use the thermometer as per manufacturer instructions.
• Normal body temperature averages around 98.6°F (37°C), but fever is typically 100.4°F (38°C) or higher.
• If fever persists or is very high, seek medical attention.

This summary covers how to use various types of thermometers to check for fever accurately at home.