3.6 · Part II
Supported Application · Guided Entry to Today's Problem
Convert Measurements within the Same System · Conversion factor
- Identify the conversion factor (e.g. 1 ft = 12 in, 1 km = 1,000 m)
- Larger to smaller unit: Multiply by the conversion factor
- Smaller to larger unit: Divide by the conversion factor
- Convert Measurements within the Same System (Convertir medidas dentro del mismo sistema) — Rewriting a measurement in a different unit of the SAME system, such as feet into inches or liters into milliliters.
- Conversion factor (Factor de conversión) — The ratio that links two units in the same measurement system, such as 12 inches to 1 foot. Within one system it is exact.
- Unit ratio (Razón unitaria) — A ratio that compares an amount to exactly 1 unit of another quantity, like 12 inches to 1 foot.
- Convert (Convertir) — To change a measurement from one unit to another without changing how much it is.
- Measurement system (Sistema de medidas) — A family of units that go together — customary units like inches and feet, or metric units like milliliters and liters.
- Double number line (Recta numérica doble) — Two number lines lined up so matching tick marks show two units for the same amount.
- A common mistake when converting within a measurement system is choosing the operation by habit instead of by unit size — multiplying every time. Converting 36 inches to feet by multiplying gives 36 × 12 = 432 feet, taller than a 40-story building. Ask first which unit is smaller: it takes MORE small units to make the same amount, so going to a smaller unit multiplies, and going to a larger unit divides.
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1 MULTIPLE CHOICE
A child is 4 feet tall. A ride requires 44 inches. Can the child ride?
- AYes, because 4 feet = 48 inches, which is more than 44
- BNo, because 4 is less than 44
- CYes, because 4 feet = 44 inches exactly
- DYou cannot compare feet and inches
✏️ Workspace & Solution Steps
Writing Task: Justify why your mathematical solution is accurate and complete.
3.6 · Part II
On-Level Application · Standard Rigor
Convert Measurements within the Same System · Conversion factor
- Identify the conversion factor (e.g. 1 ft = 12 in, 1 km = 1,000 m)
- Larger to smaller unit: Multiply by the conversion factor
- Smaller to larger unit: Divide by the conversion factor
- Convert Measurements within the Same System (Convertir medidas dentro del mismo sistema) — Rewriting a measurement in a different unit of the SAME system, such as feet into inches or liters into milliliters.
- Conversion factor (Factor de conversión) — The ratio that links two units in the same measurement system, such as 12 inches to 1 foot. Within one system it is exact.
- Unit ratio (Razón unitaria) — A ratio that compares an amount to exactly 1 unit of another quantity, like 12 inches to 1 foot.
- Convert (Convertir) — To change a measurement from one unit to another without changing how much it is.
- Measurement system (Sistema de medidas) — A family of units that go together — customary units like inches and feet, or metric units like milliliters and liters.
- Double number line (Recta numérica doble) — Two number lines lined up so matching tick marks show two units for the same amount.
- A common mistake when converting within a measurement system is choosing the operation by habit instead of by unit size — multiplying every time. Converting 36 inches to feet by multiplying gives 36 × 12 = 432 feet, taller than a 40-story building. Ask first which unit is smaller: it takes MORE small units to make the same amount, so going to a smaller unit multiplies, and going to a larger unit divides.
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1 DRAG SORT
Sort each conversion by what happens to the NUMBER.
- 7 feet → inches
- 84 inches → feet
- 2 liters → milliliters
- 5,000 milliliters → liters
- 3 pounds → ounces
- 64 ounces → pounds
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2 MULTIPLE CHOICE
Diamond needs 4 liters of water. Her bottle holds 500 milliliters. How many times must she fill it?
- A8 times
- B4 times
- C2 times
- D40 times
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
How many inches are in 2 feet?
- A24
- B14
- C10
- D12
✏️ Workspace & Solution Steps
Writing Task: Justify why your mathematical solution is accurate and complete.
3.6 · Part II
Extension & Non-Routine Application
Convert Measurements within the Same System · Conversion factor
- Identify the conversion factor (e.g. 1 ft = 12 in, 1 km = 1,000 m)
- Larger to smaller unit: Multiply by the conversion factor
- Smaller to larger unit: Divide by the conversion factor
- Convert Measurements within the Same System (Convertir medidas dentro del mismo sistema) — Rewriting a measurement in a different unit of the SAME system, such as feet into inches or liters into milliliters.
- Conversion factor (Factor de conversión) — The ratio that links two units in the same measurement system, such as 12 inches to 1 foot. Within one system it is exact.
- Unit ratio (Razón unitaria) — A ratio that compares an amount to exactly 1 unit of another quantity, like 12 inches to 1 foot.
- Convert (Convertir) — To change a measurement from one unit to another without changing how much it is.
- Measurement system (Sistema de medidas) — A family of units that go together — customary units like inches and feet, or metric units like milliliters and liters.
- Double number line (Recta numérica doble) — Two number lines lined up so matching tick marks show two units for the same amount.
- A common mistake when converting within a measurement system is choosing the operation by habit instead of by unit size — multiplying every time. Converting 36 inches to feet by multiplying gives 36 × 12 = 432 feet, taller than a 40-story building. Ask first which unit is smaller: it takes MORE small units to make the same amount, so going to a smaller unit multiplies, and going to a larger unit divides.
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1 MULTIPLE CHOICE
A rope measures 7 feet. Using 1 foot = 12 inches, how long is the rope in inches?
- A84 inches
- B19 inches
- C7 inches
- D0.58 inches
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
A tap fills 250 milliliters every 10 seconds. Will it fill a 3-liter jug in under 2 minutes?
- AYes — it delivers 3,000 mL in 120 seconds, exactly filling the jug at the 2-minute mark
- BNo — 250 mL in 10 seconds is far too slow for 3 liters
- CYes — 3 liters is only 300 mL, so it takes 12 seconds
- DThere is not enough information to tell
✏️ Workspace & Solution Steps
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3 OPEN RESPONSE
Michael's mother is setting four fence posts. Each post needs 250 ounces of concrete mix, one bag holds 80 ounces, and each bag needs 1 quart of water. How many bags and how many cups of water does she need? Show your conversions.
✏️ Mathematical Justification & Response
Writing Task: Justify why your mathematical solution is accurate and complete.