Determine Lengths in Centimeters, Millimeters, and Inches
0 Comments


In this lesson we will measure lengths and centimeters, millimeters and inches. For part a we’re asked to measure the length of the line segment AB using centimeters as te unit of comparison. This is a centimeter ruler, which means each large unit has a length of one centimeter. To measure the length of segment AB we line up point A with zero on the ruler and then measure the length out to point B. Notice how the length of the segment AB is between five and six centimeters. Also notice how each centimeter is cut into ten equally sized parts, or pieces. And thereforer, each smaller length or the distance between each small tick mark is equal to one-tenth of a centimeter. So to determine the length we count out to five centimeters and then count the number of small tick marks out to point B. So there’s one, two, three four, five, six, seven small tick marks out to point B, which means the length is five and seven-tenths centimeters, which we can write as a decimal, or a mixed number. As a mixed number we have five and seven-tenths centimeters. As a decimal we have five point seven centimeters. For part b, we’re asked to measure the length of base B of the isosceles triangle using millimeters as a unit of comparison. And the given ruler is a centimeter ruler. So we need to know that one centimeter is equal to ten millimeters and therefore, one millimeter is equal to one-tenth of a centimeter. We learned from the previous example the distance between each small tick mark is equal to one-tenth of a centimeter, which is also equal to one millimeter. So to determine the length of base b, we’ll lineup one end with zero on the ruler and then count the number of small tick marks out to the other end, which is here. And again each centimeter is equal to ten millimeters. So we have ten, twenty, thirty, thirty-one, thirty-two millimeters as the length of base b. Now for the last example, we’re asked to measure the length L of the base of the box using inches as the unit of comparison. So now we have an inch ruler meaning the length between each larger unit is one inch. To begin we line up one end with zero on the number line and then measure the length. Well notice how the length is between four and five inches. To determine the exact length we need to cut one inch into smaller parts or pieces. So from four inches to five inches we’ll divide this inch into smaller equally sized parts, or pieces. If we divided them into two equally sized parts, or pieces each smaller piece is equal to one-half an inch. If we divide this into four equal size parts or piecea, each smaller unit is equal to one-fourth of an inch. And this is what we need in order to measure this length. Notice how the exact length is four and one-fourth inches. For some lengths we may need to cut the inch into smaller parts or pieces, but for this length, cutting one inch into four equal size parts, or pieces was enough to determine the exact length. We may also recognize that one-fourth is equivalent to twenty-five hundredths and therefore, we can also express four and one-fourth inches in decimal form as four point two, five inches. I hope you found this helpful.

Leave a Reply

Your email address will not be published. Required fields are marked *