Lesson 9

The purpose of this Estimation Exploration is for students to make sense of times that would be reasonable with only the hour hand as a reference on a clock. 

• Groups of 2
• Display image.
• “What is an estimate that’s too late?” “Too early?” “About right?”
• 1 minute: quiet think time

• “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Record responses.

• “How did you know that the hour was 1?” (The hour hand passes between 1 and 2 as the time goes from 1:00 to 2:00.)
• Consider asking:
  • “How did you decide how far past 1:00 it was?” (It has to be a little past 1:30 since the hour hand is a little more than halfway between the 1 and the 2.)

The purpose of this activity is for students to tell and write time to the nearest minute. They learn that there are 60 small tick marks around the clock to show each of the 60 minutes in 1 hour. The work here gives students a reason to attend to the features of the clock and use them to tell time more precisely (MP6). The synthesis provides an opportunity to discuss how the clock does not indicate whether the time is a.m. or p.m.

• Groups of 2
• “Take some time to think about the time Lin and Diego think this clock is showing.”
• 1-2 minutes: quiet think time
• “Talk to your partner about who you agree with and why.”
• 2 minutes: partner discussion
• Monitor for students who notice that the minute hand is not pointing to the 7 or the 8 but is in between the two numbers.
• Invite students to share their responses and reasoning.
• “There are 60 small tick marks around the clock to show each of the 60 minutes in 1 hour. We know it is 1:37 since the minute hand is at the thirty-seventh tick mark.”

• “Work with your partner to determine what time is shown on each of these clocks.”
• 2-3 minutes: partner work time
• Monitor for different ways that students determine the minutes, such as:
  • Counting by 5 and then by 1
  • Starting at a time they know and counting on or back

If students tell the time to the nearest 5 minutes, consider asking:

• “Tell me how you found the time.”
• “How could you use a time that you know to find the time to the nearest minute?”

• Invite students to share how they knew the time on each clock. Emphasize strategies for telling time to the nearest minute.
• Consider asking:
  • “Were there any times that confused you at first or were harder to tell?” (On the fourth clock, I thought the hour might be 8.)
  • “Does anyone have suggestions for how to handle some of the times that could create confusion?”
• If not mentioned by students, ask: “Were you able to tell whether the time on the clock was a.m. or p.m.?” (No, the clock doesn’t tell us whether it is a.m. or p.m., we’d need more information to know that.)

The purpose of this activity is for students to tell and write time to the nearest minute as they draw times on blank clocks.

• Groups of 2
• “Let's use what you know about telling time to the nearest minute to practice writing times on clocks.”
• “What are some important things to remember when you are drawing the time on a blank clock?” (Show the difference between the minute and hour hand clearly. Be careful in drawing the location of each hand.)
• 30 seconds: partner discussion
• Share responses.

• “As you work, discuss your work and any questions you have with your partner.”
• 5-7 minutes: partner work time

• “Tell me about how you decided where to draw each hand.”
• “How could you make it easier to tell the hour hand from the minute hand?”

• Invite students to share the times they drew on the clocks. Emphasize how they distinguish between the hour and minute hands for someone else to be clear on the time they are showing.
• Consider asking:
  • “Were there any times that confused you at first or were harder to show?” (For 3:18 I had to draw the hands really close together.)
  • “Does anyone have suggestions for how to handle some of the times that might be hard to show?”
• “When you were drawing a time for your partner, what did you have to keep in mind?” (To make sure to show the difference between the minute and hour hands clearly, to be precise in what minute the hand was pointing to.)