STILLWATER CROSSING · THE COURSE NOTES · BRIDGE MATH 5/6

Week 19 · Metric Measures and Decimals

This week

Lessons 85, 86, 87, 88, & 90

Papers

Test 9 to do at home

Method

No calculators, ever · show every step

Instructional notes

Metric Linear Measures

The metric system is another way to measure. It is used in many places around the world. The meter is the metric unit for length. The metric system utilizes prefixes to form larger or smaller units like centimeters or kilometers.

prefixes kilo hecto deca unit deci centi milli abbreviations k h da m d c m values 1,000 100 10 1 0.1 0.01 0.001

Example

Fill in the blanks with the correct numbers.

1 cm = 0.01 m 1,000 m = 1 km 1 mm = 0.001 m 1 dam = 10 m 1 dm = 0.1 m 1 hm = 100 m

Write the correct abbreviation in the blank.

1 km = 1,000 m 0.01 m = 1 cm 0.001 m = 1 mm

Practice

Fill in the blanks. 1 hm = 100 m 1dm = 0.1 m 1 dam = 10 m 1000 m = 1 km

Instructional notes

Converting Metric Measures

To convert metric measures: • Write metric prefix abbreviations from largest to smallest. Be sure to include the unit. • Determine direction Moving left = divide Moving right = multiply • How many units are being moved? • Move the decimal

EXAMPLE PROBLEM

Convert each metric measure.

Practice

Convert each metric measure.

750 m = ___7,500___dm 124 mm = __0.124____m

56 cm = __0.0056___hm 5,637 mm = ___0.005637_km

Instructional notes

Adding and Subtracting Decimals

To add or subtract decimals: • Rewrite vertically, lining up the decimal points • Add zeros to fill any empty spaces so all numbers are the same length • Add or subtract • Place the decimal point in the answer directly below the other decimal points

EXAMPLE PROBLEM

Add or subtract.

Practice

Add or subtract.

Instructional notes

Multiplying Decimals by Whole Numbers

To multiply a decimal by a whole number: • Multiply, ignore the decimals • Count the total number of digits to the right of the decimal • Place the decimal in the product by counting that many places from the right.

Example

Practice

Multiply.

48.04 × 8 = 384.32 89.5 × 16 = 1,432

0.042 × 37 = 1.554 4.6 × 32 = 147.2

Quick Review

Complete the chart by multiplying or dividing.

Complete the chart. Fraction Decimal Word Form 3 0.03 Three hundredths 100 1 66 1.67 One and sixty-seven hundredths

111 20

9 20.9 Twenty and nine tenths 11

Why did we do that? Why is it important to line up decimal points when adding or subtracting decimals? What could go wrong if you didn’t?

Suggested Answer: "If you don’t line up the decimal points, you end up adding digits from different place values together (like adding tenths to hundredths), which gives a wrong answer. Lining up ensures each column represents the same place value."

Homework this week

Work-text	Lesson 88	Lesson 85	Lesson 86	Lesson 87	Lesson 90
Speed drill	85	86	87	88	90

Terms on the record

Term	Meaning
meter	around the world. The meter is the metric unit for length. The metric
length	around the world. The meter is the metric unit for length. The metric
zeros	• Add zeros to fill any empty spaces so all numbers are the same

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