Downtown Campus Biology > Biology 181 > Lesson 1 Activities > Introduction to the Scientific Method - page 3

Now let's try converting that measurement into the other units. Record these on Question #3 on your worksheet.

• Converting 18.9 cm to millimeters: Since there are 10 mm in 1 cm, we can multiply 18.9 cm times 10, and we get 189 mm. Notice that multiplying by 10 means moving the decimal point one place to the right.
  
  
• Converting 18.9 cm to meters: Since there are 100 cm in 1 m, we can divide 18.9 cm by 100, and we get 0.189 m. Notice that dividing by 100 means moving the decimal point two places to the left.
  
  
• Converting 0.189 m to kilometers: Since there are 1000 meters in 1 km, we can divide 0.189 m by 1000, and we get 0.000189 km. Notice that dividing by 1000 means moving the decimal point three places to the left.

If you are still confused, try making a "columns chart" like this to help you convert from one unit to another. The lines show where decimal points can go, the spaces between the lines show where numbers go, and the units at the bottom show where to move the decimal point. The numbers stay in the same columns, but we move the decimal point around. (When needed, fill in the empty columns with zeros. The zero before the decimal point is optional.)

Other students find it easier to think of moving the decimals up and down a "staircase".

This is what 0.189 m would look like on the staircase.

To convert 0.189 m to centimeters, move the decimal down the staircase:

You can see that 0.189 m =18.9 cm.

To convert 0.189 m to kilometers, move the decimal up the staircase:

You can see that 0.189 m = 0.000189 km.

If making a chart like the "columns chart" or the "staircase" helps you with the conversions, please use it! Lots of other students do! (You can copy your favorite to the “charts for conversions” under Question #4 on your worksheet.) You can also set up the same chart for doing conversions using liters and grams, since the prefixes stay in the same columns.

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