Elapsed Time — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
In Grade 4 conversions, 1 hour equals 100 minutes when measuring elapsed time.
Corrected: In Grade 4 conversions, 1 hour equals 60 minutes when measuring elapsed time.
Grade 4 students must use 60 (not 100) for the minute-to-hour relationship since clocks are based on a sexagesimal system.
2. Fix the sentence:
For Grade 4, 90 minutes is the same as 1 hour 50 minutes of elapsed time.
Corrected: For Grade 4, 90 minutes is the same as 1 hour 30 minutes of elapsed time.
Grade 4 conversions take out groups of 60 minutes to find whole hours, then keep the remainder as leftover minutes.
3. Fix the sentence:
A Grade 4 duration of 2 hours 15 minutes converts to 215 minutes total.
Corrected: A Grade 4 duration of 2 hours 15 minutes converts to 135 minutes total.
Grade 4 students convert hours to minutes first by multiplying by 60, not by writing the digits side by side.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. In Grade 4, 1 hour equals 60 minutes of elapsed time.
Grade 4 students learn that an hour always contains 60 minutes, the foundation for every conversion.
2. A Grade 4 duration of 90 minutes equals 1 hour and 30 minutes.
Grade 4 conversions split minute totals into whole hours (groups of 60) and leftover minutes.
3. In Grade 4, 2 hours 15 minutes is equal to 135 minutes total.
Grade 4 students change hours into minutes by multiplying by 60 before adding the leftover minutes.
4. For Grade 4, 1 minute equals 60 seconds when converting time units.
Grade 4 students extend the 60-rule from minutes-per-hour to seconds-per-minute for full unit conversions.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Explain to a Grade 4 student how to convert 3 hours 45 minutes into total minutes.
Sample answer: I multiply the hours by 60 because each hour has 60 minutes, so 3 hours times 60 equals 180 minutes. Then I add the leftover 45 minutes to get 180 + 45 = 225 minutes total. So 3 hours 45 minutes equals 225 minutes in Grade 4 time conversions.
Grade 4 conversions follow a two-step rule: change hours to minutes, then add any remaining minutes to the product.
2. How would a Grade 4 student convert 200 minutes into hours and minutes of elapsed time?
Sample answer: I divide 200 by 60 because every 60 minutes is one hour. 200 divided by 60 equals 3 with a remainder of 20, so 200 minutes equals 3 hours 20 minutes. The quotient is the number of full hours and the remainder is the leftover minutes in Grade 4 elapsed time.
Grade 4 students convert minutes back to hours by dividing by 60 and reading the quotient and remainder as hours and minutes.