# Linear Measurement

Math TEKS - Linear Measurement:
3.11A Use linear measurement tools to estimate and measure lengths using standard units.
3.11B Use standard units to find the perimeter of a shape.

Core Components:
Estimates length before measuring.
Measures in standard units (in, ft, yd) and metric units (cm, dm, m).
Uses tools such as a ruler (customary or metric), yardstick, meter stick, and tape measure.
Understands that 12 inches = 1 foot, 3 feet = 1 yard, 36 inches = 1 yard, and 100 centimeters = 1 meter.
Uses any starting point on a ruler.
Relates units of measurement to benchmark objects.
Understands that perimeter is the distance around a shape.
Uses the TAKS Mathematics chart regularly when solving measurement problems.
Uses tools to measure and find perimeter.
Expresses perimeter in linear units and understands why this is necessary.

Concepts and skills in measurement all deal with making comparisons between what is being measured and some suitable standard of measure. Key to the development of skills in measurement is ample experience with measuring activivities. Also important is the reality that measurement is never really exact, that even the most careful measurements are approximations. Children need to evaluate when their measurements are "close enough". Children also need practice making estimates in measurement.

In previous grades, students learned to measure using mostly "non-standard" units of measure such as paperclips, hands, blocks, etc. Standard units should emerge as a convenient extension of non-standard units. It makes sense that children become comfortable with both the metric and English (customary) systems. We live in a "bilingual" measurement world, and children need to be familiar with both ways of measuring.

Day 1:
Second grade focuses on selecting and using nonstandard units to determine length, and on identifying (and using to measure length) concrete models that approximate standard units of length. Standard units are introduced in third grade. Also, the use of rulers, yard sticks, measuring tape, and meter sticks are introduced in third grade to estimate length and to measure length.

Review what the kids already know about non-standard units of measure from 2nd grade. Use the linear measurement cards made from the Lone Star math questions to guide students to choosing one non-standard measurement tool for each of the linear measurements. These will be the ones referred to for the rest of the unit. Be sure to reinforce the idea that measurement is never really exact, that even the most careful measurements are approximations. Lead students to understand that, by having something they can use to approximate the length of an object, they will always have a tool for coming close to an accurate measurement. Stick to ONLY the yard, foot, inch, millimeter, centimeter, decimeter, and meter.

Use this time to introduce the concept of the "customary" and "metric" system of measurement.

Once students understand these approximations, bring out the "tools" we will use to measure length: yard stick, inch ruler, centimeter ruler, and meterstick. Have students use these in groups to measure the body parts listed on the Lone Star cards. Discuss how close or how far off the measurements were and the reason why this would be the case. (ex. some students are smaller than other, some people have bigger hands, etc.). Again, reinforce the idea that these are approximate measurements. Have students create a chart of these measurements in their math journals.

Display the Lone Star cards in your room for reference. Be sure to display these in a way that the students can see the difference in the customary and metric unit of measurement.

Day 2 and 3:
This lesson begins to show students how to use the ruler to measure inches through exploration of "Broken Rulers".

Day 4:
This lesson is similar to the previous one but focuses more on the metric unit of measurement.

Day 5:
Linear Measurement Scavenger Hunt:

Once students get the idea of measuring with their rulers, show them how to use the ruler on the Mathetmatics Chart that will be used for TAKS. Have them practive using the worksheet from "Step Up to the TAKS" page 72. If you do not have any of these charts, you can print them.

Day 6:
Students will need to be able to choose which unit of measurement they would need to measure various lengths. Use this powerpoint to discuss this idea and practice.

Day 7: TAKS Released Test
Day 8:
Use this day to make sure students understand the concept of 1/2 and 1/4 on the ruler. Each class will make a giant "ruler" with each students creating one of the inches on the ruler. Label sentence strips for each child (a number on each end that will create a full foot, I will show you what I mean). Pass out a sentence strip to each student. Show them how to find the 1/2 way point on their "inch" and label it. Do the same thing for the 1/4 and the 3/4 mark. When done, tape the sentence strips end to end to make a huge ruler. For fun, try measuring something, like the length of the classroom.

When teaching this, be sure to emphasize that 1/2 inch means the SPACE, not the LINE.

Day 9: Review and Test

Activities to do with Picture Books:

Math Exemplars:
These are provided by RRISD and can be used as Problem Solving lessons.