This is a step that must be mastered by the students to compute elapsed time.
The student must be able to convert so many minutes to equivalent hours and minutes.
After students compute the total elapsed time it may possess minutes over 60. For example, if Ralph started raking the yard at 7:10 AM and completed this task at 9:25 AM, how much time did Ralph spend raking the yard?
Well...50 total minutes to 8 AM. 1 hour from 8 Am to 9 AM. 25 more minutes after 9. So, the student adds the total minutes and arrives correctly at 75 minutes with 1 total hour. Hence, the answer is 1 hr 75 minutes. But, the student can't leave the problem like that - no one says 1 hour and 75 minutes. Converting the 75 minutes to equivalent hours and minutes yields: 1 hour and 15 minutes equals 75 minutes. Consequently, 1 hour + 1 hour and 15 minutes equals 2 hours and 15 minutes the total time Ralph raked the yard,
The student must possess this skill set. They are only grasping this task by directly practicing the skill. These sheets allow the student to mentally compute total minutes to an equivalent hours and minutes, as shown with Ralph.
The student should reach the black star on the answer key to demonstrate mastery in 5 minutes.
However, the teacher should help the student with quick mini lessons. The student must understand multiples of 60 is the key - since Time is a Base 60 system. So, they must know 1 hour = 60 minutes... 2 hours is 120 minutes. Total minutes OVER 60 but less than 120, the student can mentally subtract that computation very quickly with short practice sessions. The same is true with minute totals above 120 but less than 180 to compute 2 hours and some minutes.
It always amazes me that there are teachers that want children/students to be good at a skill, but do not practice with them...communicate thinking...that permeates their success at the task. If a student does not know a skill that can only mean one thing...that student requires more concerted practice, not less!
Practice a little each day...send one sheet home for practice...use the other for an assessment. The student should know how to subtract prior to doing this skill. It is a layered skill that precedes this skill. FYI.
Best to you and your students.