Place the following set of numbers in ascending order. 
20, -7, 5,-5 ,12, 4, 15

The easiest way is put degree marks after each one

20°, -7°, 5°, -5° ,12°, 4°, 15°

and remember that 

A LOWER (COLDER) TEMPERATURE IS A LOWER NUMBER

and

A HIGHER (WARMER) TEMPERATURE IS A HIGHER NUMBER

The lowest temperature is -7°
The next to lowest is -5°, then 4°, 5°, 12°, 15°, 20°,
with 20° as the highest temperature.  So the numbers in order:

-7, -5, 4, 5, 12, 15, 20

Although the "temperature method" works perfectly, here is the
way you were probably taught:

Draw a number line, where 0 is in the middle, the negative 
numbers go to the left and the positive numbers go to the right.


-------------------------------------------------------------------------------------------
-8 -7 -6 -5 -4 -3 -2 -1  0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15 16 17 18 19 20 21  



Locate and circle these numbers on the number line


----o-----o--------------------------o--o---------------------o--------o--------------o----
-8 -7 -6 -5 -4 -3 -2 -1  0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15 16 17 18 19 20 21 


Write them as the appear left to right on the number line.

-7,-5, 4, 5, 12, 15, 20

Same results as with the "a lower temperature is a lower
number and a higher temperature is a higher number."

Edwin