Grade 7

Theory

Temperature Conversion from Fahrenheit to Celsius

The metric system uses the Celsius scale to measure temperature. However, temperatures are still measured on the Fahrenheit scale in the U.S.

Water freezes at 0^o Celsius and boils at 100^o Celsius which is a difference of 100^o.

Water freezes at 32^o Fahrenheit and boils at 212^o Fahrenheit which is a difference of 180^o.

Therefore each degree on the Fahrenheit scale is equal to or degrees on the Celsius scale.

How to convert Fahrenheit temperatures to Celsius

Subtract 32^o to adjust for the offset in the Fahrenheit scale.

Multiply the result by .

Example: convert 98.6^o Fahrenheit to Celsius.
98.6 - 32 = 66.6
66.6 = = 37^o C.

There is a mental math method to approximate the Fahrenheit to Celsius conversion. The ratio of 5/9 is approximately equal to 0.55555....

How to approximate the conversion of Fahrenheit temperatures to Celsius with mental math.

Subtract 32^o to adjust for the offset in the Fahrenheit scale.

Divide the Celsius temperature by 2 (multiply by 0.5).

Take of this number ( ) and add it from the number above.

Example: convert 98.6^o F to Celsius.
98.6 - 32 = 66.6
66.6
33.3
33.3 + 3.3 = 36.6 which is an approximation of the Celsius temperature

Note: This lesson includes temperatures that use negative numbers. Negative numbers follow a pattern that is opposite of positive numbers. The number -20 is smaller than the number -10. Example of counting with negative and positive numbers: -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5

Example of converting negative Fahrenheit temperatures to Celsius

Convert -4^o F to Celsius.

-4 - 32 = -36

-36 = = -20^o C