Explain why, when you have a fever, you have to keep a thermometer in your mouth for a certain length of time in order to read your correct temperature.

Because the certain period of time is needed for reaching the right temperature. After the first seconds of placing the thermometer under the tongue, readings will continue to increase and the F (or C) symbol will flash during measurement.

Explanation:

# Checking our  body’s temperature with a thermometer is an easy way to see if a fever is present. There are many different types of thermometers we can use to measure temperature. When using any kind of thermometer, we need to follow the instructions that come with the thermometer in order to read the correct temperature.

# The question above is about how to use a digital thermometer, which can be used three different ways, including oral, rectal, axillary. To keep a thermometer in the mouth (place it under the tongue) for a certain length of time is the oral way to use it. This method is used for adults and children 4 and over who are able to hold thermometer in mouth. So, we call this kind of thermometer as "digital oral thermometer".

# Using a digital oral thermometer, we should follow the followings:

   1- Wash the hands with soap and warm water.

   2- Use a clean thermometer, one that has been washed in cold water, cleaned with rubbing alcohol, and then rinsed to remove the alcohol.

   3- Do not eat or drink anything for at least five minutes before taking the temperature because the temperature of the food or beverage could make the reading inaccurate. It is neccesary to keep the mouth closed during this time.

   4- Place the thermometer tip under the tongue.

   5- Hold the thermometer in the same spot for about 40 seconds.

   6- Rinse thermometer in cold water, clean it with alcohol and rinse again.

# In the instruction N5: Readings will continue to increase and the F (or C) symbol will flash during measurement. Usually, the thermometer will make a beeping noise when the final reading is done (usually about 30 seconds). If we are keeping track, record the temperature and the time.

And the MOST IMPORTANT THING is: we should add a degree to oral reading for the most accuracy. Rectal temperatures are considered most accurate indication of the body’s temperature.