A giant armadillo has a mass of 39 kilograms. What is the giant armadillo's mass in grams? (1 kilogram =...

1. TRANSLATE the problem information

• Given information:
  • Giant armadillo mass: 39 kilograms
  • Conversion factor: 1 kilogram = 1,000 grams
• Find: Mass in grams

2. INFER the conversion strategy

• Since we're converting from a larger unit (kilogram) to a smaller unit (gram), we multiply by the conversion factor
• Strategy: \(39 \text{ kg} \times 1,000 \text{ g/kg} = ? \text{ grams}\)

3. Calculate the result

• \(39 \times 1,000 = 39,000\)
• The multiplication creates 39,000 grams

Answer: 39,000 grams

Why Students Usually Falter on This Problem

Most Common Error Path:

Weak INFER reasoning: Students incorrectly think that since kilograms are "bigger" than grams, they should divide rather than multiply.

They reason: "I have a big number (39) and big units (kg), so to get smaller units (g), I should make the number smaller by dividing: \(39 \div 1,000 = 0.039 \text{ grams}\)."

This leads to confusion because 0.039 grams would make the armadillo impossibly light, but students may not catch this unrealistic result.

The Bottom Line:

The key insight is remembering that when converting to smaller units, the number gets larger (more of the smaller units are needed to represent the same quantity). Students who forget this directional relationship with unit conversion often choose the wrong operation.