# Clock Facts

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## Objective

SWBAT create clocks prior to calculating elapsed time on an analog clock.

#### Big Idea

Students calculate elapsed time using analog clocks.

## Warm Up

10 minutes

Using a large analog clock, I set the time to 8: 47. "What time does this clock say?" I chose this time because I want to see if students are able to tell time, to the minute, accurately.  I continue by setting the clock to different times to probe student prior knowledge.  I am listening for time vocabulary, words such as half past and quarter after.

This review of time and vocabulary is familiar to my students, and it showed they retained a second grade understanding.  We then move to recording vocabulary and terminology in their math journal, collecting words we would be using in this unit including elapsed time, half past, a quarter till, and language specific to application (e.g., 8:15 a.m., fifty-nine).

Students are able to explain why the number 72 would not be used when measuring time, stating there are only sixty minutes in an hour.

## Create Clocks

25 minutes

Because many of my students share they do not have analog clocks at home, I decide it would be beneficial to have them make clocks to use at home for homework and practice with time. Using an analog clock also allows me to create a visual connection to quarter hours by shading in the one fourth sections which can be used to make connections to fractions in third grade.

I give the students a circle to cut out for the clock and demonstrate folding the circle to define the quarter hours, and colored these sections different colors.  As the students follow my model, we practice describing the quarter-hour sections as fourths. It is important to make explicit connections to help students make the transfer and apply their fraction knowledge. While the students work on their clocks, I use this time as an informal assessment to circulate and question students knowledge of time. I ask questions to small groups and individual students including:

• What are the differences in the hands?
• What do the numbers mean for hours?
• What do the numbers mean for minutes?
• How can I figure out how much time is between two numbers?

Telling time with the quarter hour terms challenges the students, but they tell time using the word fifteen.  The clocks provide practice with quarter hour references and something I will continue to reinforce through different lessons on measuring time.

## Elapsed Time Using Analog Clocks

15 minutes

To demonstrate their understanding of elapsed time on an analog clock, the students use individual math clocks to compute elapsed time.  They are not using the ones they made, as the hands do not rotate easily and the precision of minute marks isn't in place.

I begin by asking questions using hours for elapsed time, based on events that take place at school.  I use the familiar shared experiences of our school day, so that all students can relate to the problem.  When the students demonstrate they can solve these problems without needing to use the clocks, I move on to questions to include half hours.  These are followed by questions including quarter hours and then minutes.

Students use strategies of counting by fives and adding the extra minutes to solve the problems.

## Wrap Up

5 minutes

To close, I keep the overall focus on reviewing the concept the students struggled with the most, quarter hours.  The students are asked to set their math clocks, to various "quarter after" and "quarter till" times rapidly.

Within this, I also ask how much time has elapsed from one given time to the next.  For example, if they have set their clocks to 7:45 and the next time given is 8:15, I ask them to tell me how much time has elapsed. I also include practice for students to set clocks a half an hour earlier or later from the quarter hour marks such as set your clock a half an hour after 8:15.

The students engaged in the quick pace of this game type review.