**Category : **3rd Class

**LEARNING OBJECTIVES**

- This lesson will help you to:—
- understand non-uniform units.
- revise standard units of length like millimeter,
- centimeter and meter.
- choose appropriate standard unit of length.
- measure objects using standard unit of length.
- estimate length of a given object in standard units.
- verify length of a given object by measuring.
- use a ruler for measuring length.
- relate centimeter and meter.

** **

**Real life examples**

- All clothes are stitched by taking body measurements using measuring tapes.
- Measurement of length helps in knowing the distance between two places.
- Carpenters use measuring tapes to measure length of wooden furniture in order to construct them.
- All students in your class are of different heights.
- The size of your shoe is based on the length of your feet.

Meters (m) is the unit which is widely used in various races like car race, bicycle race.

**AMAZING FACTS**

- Fathom: “The length of the outstretched arm”, about six feet. Water depth is measured in fathoms.
- Span: “The distance between the thumb and little finger of an extended hand” roughly nine inches.

** **

**QUICK CONCEPT REVIEW**

Rulers are used to measure small objects.

You can measure the length of the pencil using a ruler.

This pencil is 5 cm long. Try measuring your pencil.

Measuring tapes are used to measure large objects.

Measuring tape is also used to measure body parts.

Examples:-

- Have you ever measured your fingers? The middle finger is 4.5 cm long. Try measuring your fingers!
- Have you ever measured your waist? Oops!! Looks like Hippopotamus is having short of measuring tape. Try measuring your waist and see whether you face the same problem.

**MEASUREMENT USING RULER OR MEASURING TAPES**

** **Place one end of the object with ‘0’ in the ruler/measuring tapes.

The object and the ruler/measuring tapes should be straight.

Start reading the scale on ruler/measuring tapes.

Stop reading the scale where the object ends.

Hold the last end of the object and read the scale.

**SHORTCUT TO PROBLEM SOLVING**

- Always start from '0' while using measuring instruments.
- Millimeter (mm) and centimeter (cm) are used to measure very small distance.
- Meter (m) and kilometer' (km) are used to measure large distances.

**LET’S UNDERSTAND SOME CONVERSIONS**

- 100 Centimeters = 1 Meter

100 cm =1 m

- 10 Centimeters = 1 decimeter
- 10 decimeters = 1 meter

** **

**HISTORICAL PREVIEW**

- In ancient times, various body parts were used to measure objects.
- It was the Greeks who developed the “foot” as their fundamental unit of length. It was based on an actual measurement of Hercules’ foot.
- Qutub Minar is the tallest minaret in India. It is 72.5 Meters high

** **

**Misconcept/Concept**

**Misconcept:** All the units of measuring the volume are equal.

**Concept:** Different units of measuring volume vary in their capacity. The volume must not be interchanged.

**Misconcept:** Some large rulers can measure long distances.

**Concept:** Rulers cannot be used to measure long distances, irrespective of how big the ruler be. A ruler cannot be used to measure units such as kilometers.

*play_arrow*Measurement*play_arrow*Measurement Length*play_arrow*Measurement Weight*play_arrow*Measurement Volume*play_arrow*Introduction*play_arrow*Measurement of Shorter Length*play_arrow*Measurement of Long Distance*play_arrow*Measurement of Mass*play_arrow*Measurement of Capacity of Volume

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