# Lesson: Elapsed Time: Half and Quarter Hour

Tara Smith E.l. Haynes Pcs Washington, DC
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### Lesson Objective

SWBAT compute elapsed time on a digital clock to the half and quarter hour.

### Lesson Plan

Materials Needed: pencils, Do Now worksheet, GP worksheet, and IND worksheet.

Vocabulary: digital, elapsed time, minute, interval, hour, o'clock, minute hand, and hour hand

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Do Now (10 min): Students begin with a writing exercise. The prompt should ask the student to identify their favorite time of the AM day and their favorite time of the PM day. If time allows they can draw a picture about their choices.

Opening (2-3min): Teacher begins by highlighting some of the student’s drawings/sentences. Then moves to quickly showing a demonstrate clock and pulsing the class to get focused on elapsed time. “If AJ got up at 6:45 am and arrived at school at 7:45, how much time passed until he got to school?” Make the student explain how they arrived at the answer, reference diagram on IND worksheet from previous day’s lesson if necessary.

State objective at end of the opening, “Today we are going to focus on calculating the passage of time, or elapsed time, to the hour and half hour!  Yesterday we introduced this idea but only focused on whole hour intervals. Let’s get started.”

Direct Instruction (8-10 min): The teacher directs her full attention to the students and explains the steps to calculating elapsed time.  Begin with half hour, and complete example with quarter hour.

Example 1: 8:30 am – 2:30 pm

1. Determine the start and end time, PAY ATTENTION TO AM/PM
2. Calculate the whole hours = 5 hours (Note: may need to round up/down)
3. Count up the minutes = 30+ 30 = 60  (Note: adding the difference to first hour)
4. Convert to hours, if necessary = 60 min = 1 hour (Note: 60 minutes in an hour)
5. Add to find total elapsed time = 5 hr + 1 hr = 6 hr

Example 2: 9:15 am – 11: 30 am

1. Determine the start and end time, PAY ATTENTION TO AM/PM
2. Calculate the whole hours = 1 hours (Note: may need to round up/down)
3. Count up the minutes = 45 + 30 = 75 minutes  (Note: adding the difference to first hour)
4. Convert to hours, if necessary = 75 min = 1 hour  15 min (Note: 60 minutes in an hour)
5. Add to find total elapsed time = 1 hr + 1 hr 15 min = 2 hr 15 min

Praise the students for following the steps even if they can do it mentally, this is important for the following day when we move to elapsed time to the one-minute interval.

Guided Practice (10 -15 min): Students pair up and complete 2 elapsed time problems in the same format as the teacher outlined on the board. I’ve included two sets so teachers can differentiate if needed.

Independent Practice (8 -10 min): The teacher should then begin independent practice with the worksheet that mimics the guided practice.

Closing (3-5 min): Teacher calls the attention of the students back toward the front of the class to review objective for today. Ask the class if they can explain the steps (with or without looking) to finding elapsed time. Then students complete 5 questions quiz.

### Lesson Resources

 IND elapsed quarter hour   Classwork 539 GP elapsed half and quarter   Classwork 518 GP elapsed half and quarter differeniated   Classwork 372 PM Writing   Starter / Do Now 290