This video with audio can be seen here:    • 1.4b-Placing of Dimension Systems in ...  
This video teaches two systems of placing dimensions in engineering drawing: Aligned System and Unidirectional System. You should learn both systems but use only one in a drawing. One drawing must follow either Aligned or Unidirectional system of placing dimensions. Dimensioning also requires good lettering to write the dimensions. Remember, you should only write the dimension in millimeter. No need to write the word "mm" or "millimeter", just the number. It is understood that the dimensions are in millimeters. Other important tips, never ever dimension more than what is just necessary and one dimension of the object should never be dimensioned twice, for example in two different views. Proper spacing between two dimension lines, size of the numbers relative to the size of the drawing are to be practiced.
Download Drawing Worksheet: https://drive.google.com/open?id=1lBP...