Teacher Guide: Measurement Conversions

🎯 Learning Objective 15-20 min lesson

Students will: Convert units within the customary measurement system (length, capacity, weight) and within the metric system using multiplication and division, and apply these skills to solve real-world problems.

Key Understanding: When converting to a smaller unit, multiply (more pieces). When converting to a larger unit, divide (fewer pieces). Metric conversions are based on powers of 10.

📊 Essential Conversion Facts

Customary Length

Conversion	Relationship
Inches to Feet	12 inches = 1 foot
Feet to Yards	3 feet = 1 yard
Feet to Miles	5,280 feet = 1 mile

Customary Capacity

Conversion	Relationship
Cups to Pints	2 cups = 1 pint
Pints to Quarts	2 pints = 1 quart
Quarts to Gallons	4 quarts = 1 gallon

Metric System (powers of 10)

Length	Capacity	Mass
10 mm = 1 cm	1000 mL = 1 L	1000 g = 1 kg
100 cm = 1 m
1000 m = 1 km

📦 Materials Needed

Rulers (inch and centimeter)
Measuring cups and containers
Conversion reference charts
"Gallon Guy" visual (for capacity)
Meter sticks and yardsticks

⚠ Common Misconceptions to Address

Misconception #1: Always Multiply When Converting

Students think conversion always means multiplication, so they multiply when going from smaller to larger units too.

How to Address:

Use the logic: "Are we going to more pieces or fewer pieces?" 36 inches = ? feet. There are 12 inches in a foot, so 36 inches is FEWER feet. We divide: 36 / 12 = 3 feet.

Misconception #2: Confusing Units Within Systems

Students mix up which units are larger: "Is a pint bigger than a quart?"

How to Address:

Use "Gallon Guy" for capacity. For length, use real objects: "Your foot is about 12 inches. A yardstick is 3 feet." Connect to real experiences!

Misconception #3: Treating Metric Like Customary

Students use random conversion factors instead of powers of 10 for metric.

How to Address:

Emphasize: "Metric is based on 10s! Just move the decimal." 3.5 m = 350 cm (multiply by 100). 2500 mL = 2.5 L (divide by 1000).

📝 Lesson Steps

1

Build Understanding with Real Objects (4 min)

Show a 12-inch ruler. "This is 1 foot." Show 3 rulers end-to-end. "This is 1 yard = 3 feet = 36 inches."

SAY THIS:

"When we go from feet to inches, we get MORE pieces - each foot becomes 12 inches. So we multiply. When we go from inches to feet, we get FEWER pieces - we divide."

2

Teach the Conversion Strategy (4 min)

Model: Convert 5 feet to inches.

Ask: "Am I going to a larger or smaller unit?" (Smaller - inches are smaller than feet)
Ask: "Will I have more or fewer?" (More - more inches than feet)
Action: Multiply! 5 x 12 = 60 inches

3

Introduce Capacity with "Gallon Guy" (4 min)

Draw or show the Gallon Guy visual:

1 Gallon (the whole body) = 4 Quarts (Q Q Q Q)
Each Quart = 2 Pints (P P)
Each Pint = 2 Cups (C C)

So: 1 gallon = 4 quarts = 8 pints = 16 cups

4

Metric Conversions: Move the Decimal (4 min)

SAY THIS:

"Metric is easy because it's all 10s! To convert 4.5 meters to centimeters: there are 100 cm in a meter, so multiply by 100. Move the decimal 2 places right: 450 cm!"

5

Independent Practice

Distribute worksheets. Encourage students to ask "bigger or smaller unit?" and "multiply or divide?" for each problem.

💻 IXL Skills to Assign After This Lesson

Recommended IXL Practice:

Convert inches and feet Convert feet and yards Convert cups and pints Convert quarts and gallons Convert ounces and pounds Metric length conversions Metric mass conversions Conversion word problems

🏠 Differentiation

For struggling students: Focus on one type of conversion at a time. Always use the conversion chart. Use physical objects to demonstrate.

For advanced students: Multi-step conversions (inches to yards). Challenge with mixed unit arithmetic (2 ft 5 in + 3 ft 9 in).

For home: Measure rooms in feet and convert to inches. Use measuring cups while cooking.