Make a fist with each hand. Hold each fist with the thumb at the top and the 'pinky' at the bottom.

Now stack one fist on top of the other. Historically, this is the way people measured the height of horses.

From ground level, a person would stack one hand on top of the other, and count how many hands high a horse was to the withers.

As you can likely imagine, this type of measurement is not very accurate. When buying a horse that is supposed to be 14 hands high, a person with small hands may think the horse is huge while a person with large hands may think the horse is small.

   The Goal

Here are the things you will do in this lesson.

• Identify and use referents for common linear measurements
• Identify and use referents for common area measurements
• Choose referents for SI and imperial units for area.
• Recognize situations when specific SI or imperial units for area are used.