# Measuring Lengths and Creating Line Plots

Line plots, like the one shown below, are particularly useful for showing measurement data. For example, if a class of students all measured the length of their pencils, a line plot would highlight the range and frequency of the measurements. Your children may have already encountered this type of graph in 2nd grade when recording measurements made in whole inches. In 3rd they will progress to use halves and fourths of an inch to make and record more precise measurements.

## Halves and Fourths of an Inch – Create Your Ruler

This worksheet activity  will help your children understand how inches can be sub-divided into more precise intervals.

Have your children try this measurement worksheet  where they will measure various objects to the nearest inch, nearest half inch, and nearest fourth of an inch.

Your children may not yet have been formally introduced to equivalent fractions (e.g. 2/4 = 1/2) and mixed numbers as these concepts are typically covered in greater depth in later grades. Help your children as required but try not to over complicate this exercise.

## Best Units for Measurement

Discuss different measurements with your children that would best done with different units of measurement. Have a ruler and/ or a measuring tape to hand. The illustration below has some examples although ideas that you and your children come up with are best.

## How to create a line plot

1. Take measurements and record in a table – use tally marks
2. Determine the range of the base number line
3. Determine the height of the graph (the most frequent measurement)
4. Draw and annotate the base number line
5. Mark a cross or dot for each occurrence above the measurement

Use this worksheet  to help with the creating of a line plot. It requires chart data to be counted and then graphed on a line plot.

## Base number line

Good questions to ask and things to point out as your children work through the line plot worksheets include:

• Pointing out the interval and the start and end points of the horizontal number line and how they are based on the range of values.
• How many measurements are there altogether?
• Which is the most frequent or common?
• Which is least frequent?
• What is the shape formed by the line plot? Where are the most frequent measurements?

Language is of special importance when interpreting and analysing so, as always, check that your children understand what words and terms mean as they may not have used them before e.g. “frequent” and “common”.

Your children will be required to decide what values and interval (might be halve, might be fourth?) to use on this next Activity Worksheet  which requires the creation of a line plot and includes a table of sample data which your children can organize using a tally chart before creating the line plot. Alternatively, you may wish to take your own measurements and use your own data.

## Interpreting Line Plots

Discuss with your children how in some cases, adding more data or measurements changes the shape of the line plot and this can be a better representation overall. Discuss with your children the concept of sample size. e.g. would measuring 4 or 20 students in the class be more likely to give a better representation of the height of the students in a class?

This interpreting line plots worksheet requires students to add missing data to a line plot and then to answer questions about what is shown.