Making Measurements for Line Plots
Students will be able to measure lengths of items to the nearest quarter-inch and use that data to create line plots.
- Ask students to brainstorm different types of measurements and tools used for measuring.
- Call on students to share their thinking. For example, clocks measure time in minutes and seconds, metre sticks measure meters and centimeters, and scales can measure pounds and ounces.
- Explain that when measuring you can estimate or round to a larger unit or you can be more precise. Have five students hold up their hands and quickly measure them to the nearest whole inch. Allow a few students to share their measurements.
- Ask students to think about something they could measure where being precise is less important and an example where being precise is extremely important. For example, measuring the weight of a bag of potatoes when making potato salad verses measuring the amount of medicine to give a sick baby.
- Tell students that today they are going to practise being more precise when measuring length. Instead of measuring to the nearest inch, they are going to measure to the nearest half or quarter inch.
Explicit Instruction/Teacher modeling(10 minutes)
- Show students how a ruler is divided and what the different lengths of tick marks on the ruler represent. Point out to them that some rulers have a space at the beginning before the tick marks start, so they have to be extra careful when measuring. They have to line up the item they're measuring with the first tick mark.
- Model how to carefully measure something.
- Give each student a ruler. Ask them to measure the length of a sharpened pencil to the nearest half or quarter inch. Have them switch pencils with someone nearby and measure that person's pencil.
- Explain to students that one way to organise the data or measurements from their pencil is to use a line plot. A Line plotIs a graph that shows how often data appears by placing it on a number line. Tell them it's easiest to use a line plot when comparing fewer than 25 numbers.
- Call on students to share the lengths of their pencils. Write their measurements on a board or other location where all students can see them. Explain that you've just completed the first step of making a line plot: Gathering data.
- Point out that it’s important to either organise the data from smallest to largest before starting a line plot. Ask students to identify the smallest and largest lengths and then circle them.
- Explain that by identifying these lengths they can figure out where to start their horizontal number line and when to stop it. For example, if the smallest length in 4 ½ inches the number line should start at 4 ½ not 1. If the largest length is 5 ¾ in the number line should stop at 5 ¾ not 10.
- Use a large piece of chart paper to label the parts of the number line by quarter inch starting with the smallest piece of data. Mark an X above the horizontal number line for each piece of data. Remind students that the number of X’s above the number line tells you how many times that value occurred.
Guided practise(20 minutes)
- Ask students to describe what they notice about the information on the line plot. For example, four students had pencils that were 5 ½ inches long and only one student had a pencil less than 5 inches in length.
- Tell students that they are going to create a new set of data and create a line plot for that set of data. Give students a piece of copy paper and instruct them to trace their shoe onto it. Have each student mark with a pencil or marker the top and bottom of the shoe tracing. Finally, instruct students to measure the length of their tracing from the top dot to the bottom dot and write the answer on the back of their paper.
- Have students practise measuring a few of their classmates’ tracings with a ruler and check their answers. If students disagree about a measurement, have them work together to remeasure the tracing.
- Figure out who has the smallest and largest shoe length. Give students binder paper and have students mark the number line values for the line plot.
- Split the class into two or three groups so that the students can organise a smaller amount of data at a time. Have each group write down a list of the measurements for each person in their group before students start placing X’s on their line plot.
- Instruct students to write down three observations about their line plot.
- Debrief as a whole class and have students share out their observations.
Independent working time(10 minutes)
- Give each student the Measuring the Length of Books worksheet. Review the directions with students and offer support as they complete their measurements individually.
- Assign student partnerships to complete the second table with the book values. Once they've written down their partner's book lengths, have them complete the line plot on their own.
- Preteach measuring to the nearest quarter of an inch and how to create a number line with fractions.
- Provide visual definitions for key terms and mathematical ideas.
- Group students with mixed abilities to support each other.
- Let students create their own inquiry and line plot to accompany the data. Have them present their new line plots and explain their process to the class.
- Have them serve as student-teachers and explain information to struggling students.
- Allow students to review their line plots with their partners and have them make corrections as necessary.
- Choose a few students to present their line plots and explain their process.
- Ask students to write down observations about their line plots on their worksheet.
- Collect from students their Measuring the Length of Books worksheet and use it as a formative assessment of their ability to convert data to a line plot.
Review and closing(4 minutes)
- Have students share ideas about when they can use line plots. For example, they can use line plots to compare the height of students, plants, or shoes. Also, they can compare the lengths of animals, fabric, rope, etc.
- Tell students that organizing information visually can help them draw conclusions quickly and see patterns in the information.