Measuring to the nearest half and quarter inch
Generate measurement data by measuring lengths to the nearest half and quarter inch; display the data on a line plot with a scale marked in whole numbers, halves, and quarters
Ce que l'enfant saura faire ensuite
- Measure five objects to the nearest 1/4 inch
- Create a line plot showing the lengths of classmates' pencils in half-inches
- Read a line plot and answer questions about the data
1 · Lis
You already know how to measure things and build a line plot. Now you will measure closer: to the nearest half inch, or the nearest quarter inch. A ruler splits every inch into four equal quarter marks: 1/4, 1/2, 3/4, and the whole inch. That helps tell apart pencils that look the same.
Five students measured their pencils to the nearest quarter inch: 2 in, 2 1/4 in, 2 1/2 in, 2 1/2 in, and 3 in. For each pencil, they put one X above its length on a number line marked in quarters.
Reading a line plot is counting. Each X stands for one object, so two objects with the same length get two X's stacked on that mark. The tallest stack is the most common length. Measurements grouped near one value form a cluster. To find how many more, count both stacks and subtract. Halves and quarters share one scale: 1/2 inch sits where 2/4 inch does.
Measure to the nearest quarter inch, mark an X for each length, and read the tallest stack to find the most common length.
À lire aussi
Line plots review
A line plot stacks one X per object above its measurement. Five pencils become five Xs spread across the inch marks. The tallest stack names the most common length at a glance. Each X is one real thing you measured. Plot every object exactly once. Use one scale: halves and quarters both fit on quarter-inch marks. Record how closely each length was measured. Using the same measuring method and precision helps you compare the results.
Key ideas: create and analyze a line plot for measurement data to the nearest half unit and quarter unit
Quarter inch measuring reads the small marks between whole inches. The marks divide each inch into 4 equal steps: 1/4, 1/2, 3/4, then the next whole. A pencil ending on the first mark past 5 is 5 and 1/4 inches. Line the zero end up exactly or every reading shifts. Read at eye level to dodge slant errors. Plot each reading as its own X above the matching mark. Finished plots answer questions the raw list hides.
How to Use a Ruler for Measurement
Rulers reward careful setup. Pin the zero mark to one end of the object, keep the edge snug along it, and read where the far end lands. Between whole inches, count the small steps: halves split once, quarters split twice. A stick halfway between 6 and 7 is 6 and 1/2 inches. Measure five objects the same way and your set stays fair. Rushing the zero placement is the top error. Check zero first, read second, record third.
How to Read a Ruler: 10 Steps
Reading to the nearest quarter means picking the closest mark. Marks nearer than halfway round down, marks past halfway round up. A leaf tip on the 3/4 mark past 2 reads 2 and 3/4 inches exactly. Record the whole inches plus the fraction every time. Bare fractions without wholes confuse later readers. Five careful readings beat ten hasty ones. Precision at the ruler saves rework at the plot.
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