We can measure a line segment in two ways.
(i) Using a scale or ruler only.
(ii) Using a divider and a scale or ruler.
To measure a line segment using a scale:
In general, we measure a line segment using a scale that has a mark in centimeters (cm) and inches (in). Most of the time we measure the line segments in centimeters. Each centimeter is divided into 10 small equal parts called a millimeter (mm).
1 cm. = 10mm. and 1mm. = 1 / 10cm.
A line segment has a beginning and an end. The line segment is part of a line. It has two endpoints, labeled A and B.
Let’s learn how to measure a line segment. We will use a scale to measure the line segments. Centimeters and inches are marked along the two edges of the scale.
Let’s learn to measure the length of a line segment AB in centimeters.
To measure the length of a line segment AB, we place it so that the end point A of the line segment coincides with the 0 mark of the scale.
We hold the scale correctly along the line segment. We read the mark on the scale that coincides with the end point B. Here we see that the 7th centimeter mark on the scale coincides with the end point B. Here we see that the 7th centimeter mark coincides with the end point B. Thus the length of the line segment AB is 7 cm.
When measuring a line segment, we should take some precautions. Sometimes the 0 mark on the scale does not appear because of a broken corner. If so, we can set any other point centimeter mark on the scale to end point A and measure line segment AB by counting from that centimeter mark.
Step I: Place the scale edge on the line AB so that the marking ‘0’ is at point ‘A’.
Step II: Read the scale at point ‘B’. Here the mark on the scale is 8 cm.
AB is a line segment. The length of the line segment AB is 7 cm.
To measure a line segment using a divider and a scale:
We can use a divider along with a scale to measure a line segment. We carefully open the pair of dividers and place the pointed ends of the pair of dividers on the two ends of the line segment as shown here. We lift the divider very carefully without disturbing its arms.
Now we put one end on the zero mark of the scale and let the other end rest on a certain scale of the scale as shown here.
Finally we read the length.
4th grade math activities
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