Elapsed Time — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
From 10:30 AM to 1:15 PM is 3 hours 15 minutes elapsed time in Grade 4.
Corrected: From 10:30 AM to 1:15 PM is 2 hours 45 minutes elapsed time in Grade 4.
Grade 4 students must add the hours from start to noon, then continue past 12:00 PM to the end time without double-counting.
2. Fix the sentence:
Between 11:45 AM and 2:00 PM, the duration is 1 hour 15 minutes for Grade 4 problems.
Corrected: Between 11:45 AM and 2:00 PM, the duration is 2 hours 15 minutes for Grade 4 problems.
Grade 4 elapsed time crossing noon requires counting full hours past 12:00 PM and adding remaining minutes carefully.
3. Fix the sentence:
If the movie starts at 9:50 AM and ends at 12:10 PM, the elapsed time for Grade 4 is 3 hours 20 minutes.
Corrected: If the movie starts at 9:50 AM and ends at 12:10 PM, the elapsed time for Grade 4 is 2 hours 20 minutes.
Grade 4 learners should break the elapsed time into whole hours plus leftover minutes to avoid adding an extra hour.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. From 7:20 AM to 9:20 AM, the elapsed time is 2 hours for Grade 4 students.
Grade 4 elapsed time within the same AM period is found by subtracting the start hour from the end hour when minutes match.
2. Recess starts at 11:30 AM and ends at 12:15 PM, so the duration is 45 minutes in Grade 4.
Grade 4 students cross noon by counting minutes to 12:00 PM first, then adding minutes past noon to find total elapsed time.
3. Soccer practice runs from 3:45 PM to 5:30 PM, a Grade 4 duration of 1 hour and 45 minutes.
Grade 4 elapsed time uses the count-up strategy: full hours first, then count the remaining minutes to the end time.
4. A Grade 4 field trip leaves at 8:00 AM and returns at 2:30 PM, an elapsed time of 6 hours 30 minutes.
Grade 4 elapsed time across AM and PM is found by counting whole hours through noon, then adding the leftover minutes.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Explain to a Grade 4 student how to find elapsed time when the start time is in AM and the end time is in PM.
Sample answer: I count up from the start time to 12:00 PM first to find one chunk of time, then I count from 12:00 PM to the end time to find the second chunk. I add the two chunks together. For example, 10:15 AM to 1:45 PM is 1 hour 45 minutes (to noon) plus 1 hour 45 minutes (after noon), which equals 3 hours 30 minutes in Grade 4 elapsed time.
Grade 4 students avoid mistakes by breaking AM-to-PM problems into two simpler elapsed-time pieces around noon.
2. Describe how a Grade 4 student can use a number line to solve elapsed time from 9:40 AM to 12:25 PM.
Sample answer: I draw a number line and mark 9:40 AM on the left and 12:25 PM on the right. I jump 20 minutes to reach 10:00 AM, then jump 2 hours to reach 12:00 PM, then jump 25 minutes to reach 12:25 PM. I add 20 + 25 minutes = 45 minutes, plus the 2 hours, for a Grade 4 elapsed time of 2 hours 45 minutes.
Grade 4 number-line strategies turn elapsed time into easy hops, reducing errors when crossing AM and PM.