3.7 · Part II
Supported Application · Guided Entry to Today's Problem
Convert Measurements Between Systems · Conversion factor
- Identify the conversion ratio connecting systems (e.g. 1 in ≈ 2.54 cm, 1 kg ≈ 2.2 lbs)
- Set up a ratio table or proportion aligning customary and metric units
- Multiply or divide by the conversion factor to compute the equivalent measurement
- Convert Measurements Between Systems (Convertir medidas entre sistemas) — Rewriting a customary measurement as a metric one, or the reverse, so two amounts can be compared.
- Conversion factor (Factor de conversión) — The ratio that links a unit in one system to a unit in the other, such as 1 mile to about 1.609 kilometers.
- Customary system (Sistema usual) — The measurement system used in the United States: inches, feet, miles, ounces, pounds, cups, quarts, gallons.
- Metric system (Sistema métrico) — The measurement system used in most of the world, built on tens: centimeters, meters, kilometers, grams, kilograms, liters.
- Approximately (Aproximadamente) — Close to, but not exactly equal. Conversions between systems are almost always approximate, so they use the ≈ sign.
- Ratio table (Tabla de razones) — A table of equal ratios used to scale a conversion factor up to the amount you actually need.
- A common mistake converting between systems is comparing the bare numbers without converting at all — deciding that 5 kilometers and 5 miles are the same distance because both say 5. They are not: 5 kilometers ≈ 3 miles. A second mistake is writing = instead of ≈. Conversion factors between systems are rounded (1 mile is about 1.609344 kilometers), so the result is approximate no matter how carefully you multiply.
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1 MULTIPLE CHOICE
A sign in Mexico gives a distance of 80 kilometers. Using 1 km ≈ 0.6 mi, about how far is that in miles?
- AAbout 48 miles
- BAbout 80 miles
- CAbout 133 miles
- DAbout 8 miles
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
(Lesson 3.5) Chef A uses 2 cups of cheese for every 8 crackers. Chef B uses 3 cups of cheese for every 9 crackers. Who uses more cheese per cracker?
- AChef B
- BChef A
- CThey use the same amount
- DCannot determine
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
(Lesson 3.5) Which ratio is greater: 3:4 or 5:8?
- A3:4
- B5:8
- CThey are equal
- DCannot determine
✏️ Workspace & Solution Steps
Writing Task: Justify why your mathematical solution is accurate and complete.
3.7 · Part II
On-Level Application · Standard Rigor
Convert Measurements Between Systems · Conversion factor
- Identify the conversion ratio connecting systems (e.g. 1 in ≈ 2.54 cm, 1 kg ≈ 2.2 lbs)
- Set up a ratio table or proportion aligning customary and metric units
- Multiply or divide by the conversion factor to compute the equivalent measurement
- Convert Measurements Between Systems (Convertir medidas entre sistemas) — Rewriting a customary measurement as a metric one, or the reverse, so two amounts can be compared.
- Conversion factor (Factor de conversión) — The ratio that links a unit in one system to a unit in the other, such as 1 mile to about 1.609 kilometers.
- Customary system (Sistema usual) — The measurement system used in the United States: inches, feet, miles, ounces, pounds, cups, quarts, gallons.
- Metric system (Sistema métrico) — The measurement system used in most of the world, built on tens: centimeters, meters, kilometers, grams, kilograms, liters.
- Approximately (Aproximadamente) — Close to, but not exactly equal. Conversions between systems are almost always approximate, so they use the ≈ sign.
- Ratio table (Tabla de razones) — A table of equal ratios used to scale a conversion factor up to the amount you actually need.
- A common mistake converting between systems is comparing the bare numbers without converting at all — deciding that 5 kilometers and 5 miles are the same distance because both say 5. They are not: 5 kilometers ≈ 3 miles. A second mistake is writing = instead of ≈. Conversion factors between systems are rounded (1 mile is about 1.609344 kilometers), so the result is approximate no matter how carefully you multiply.
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1 DRAG SORT
Converting between systems: sort each conversion by what happens to the number.
- Kilometers → miles
- Miles → kilometers
- Pounds → kilograms
- Kilograms → pounds
- Inches → centimeters
- Centimeters → inches
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2 MULTIPLE CHOICE
A dog weighs 31 pounds. Flea medicine comes in packages for 4–10 kg, 10–25 kg, and 25–40 kg. Which package is correct?
- AThe 10–25 kg package
- BThe 4–10 kg package
- CThe 25–40 kg package
- DNone — 31 is above every range
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
1 inch ≈ 2.54 cm. About how many centimeters is 4 inches?
- A10.16 cm
- B6.54 cm
- C1.57 cm
- D254 cm
✏️ Workspace & Solution Steps
Writing Task: Justify why your mathematical solution is accurate and complete.
3.7 · Part II
Extension & Non-Routine Application
Convert Measurements Between Systems · Conversion factor
- Identify the conversion ratio connecting systems (e.g. 1 in ≈ 2.54 cm, 1 kg ≈ 2.2 lbs)
- Set up a ratio table or proportion aligning customary and metric units
- Multiply or divide by the conversion factor to compute the equivalent measurement
- Convert Measurements Between Systems (Convertir medidas entre sistemas) — Rewriting a customary measurement as a metric one, or the reverse, so two amounts can be compared.
- Conversion factor (Factor de conversión) — The ratio that links a unit in one system to a unit in the other, such as 1 mile to about 1.609 kilometers.
- Customary system (Sistema usual) — The measurement system used in the United States: inches, feet, miles, ounces, pounds, cups, quarts, gallons.
- Metric system (Sistema métrico) — The measurement system used in most of the world, built on tens: centimeters, meters, kilometers, grams, kilograms, liters.
- Approximately (Aproximadamente) — Close to, but not exactly equal. Conversions between systems are almost always approximate, so they use the ≈ sign.
- Ratio table (Tabla de razones) — A table of equal ratios used to scale a conversion factor up to the amount you actually need.
- A common mistake converting between systems is comparing the bare numbers without converting at all — deciding that 5 kilometers and 5 miles are the same distance because both say 5. They are not: 5 kilometers ≈ 3 miles. A second mistake is writing = instead of ≈. Conversion factors between systems are rounded (1 mile is about 1.609344 kilometers), so the result is approximate no matter how carefully you multiply.
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1 MULTIPLE CHOICE
A backpack weighs 5 kilograms. Using 1 kilogram ≈ 2.2 pounds, about how much does it weigh in pounds?
- A11 pounds
- B2.27 pounds
- C7.2 pounds
- D10 pounds
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
Rosa runs a 5-kilometer race. Her cousin runs 3.5 miles. Using 1 km ≈ 0.6 mi, who ran farther?
- AThe cousin — 5 km is about 3 miles, and 3.5 miles is farther than that
- BRosa — 5 is greater than 3.5
- CThey tie exactly
- DYou cannot compare kilometers with miles
✏️ Workspace & Solution Steps
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3 OPEN RESPONSE
The Golden Gate Bridge can hold about 35,924,000 pounds. An average midsize car weighs about 1,524 kilograms. Using 1 kilogram ≈ 2.2 pounds, about how many midsize cars could be on the bridge at one time? Explain each step, and say why your answer is an estimate.
✏️ Mathematical Justification & Response
Writing Task: Justify why your mathematical solution is accurate and complete.