Transcript
L E S S O N
Measuring Time
It takes about one second to clap your hands together one time.
You will need a stopwatch. ➤ List 6 to 8 fitness activities you can do in the classroom. ➤ Estimate and record how long the first activity will take. ➤ Take turns to do each activity. Record your estimate first. Your partner will time you to the nearest second. Record your work in a table.
Activity Balancing on one foot 20 sit-ups
Estimated Time 60 seconds 80 seconds
That’s 48 seconds.
Actual Time 2 minutes 17 seconds 48 seconds
Show and Share Discuss your strategies for estimating time. How close were your estimates to the actual times? Did your strategy for estimating change as you did each activity? Explain.
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LESSON FOCUS
Tell time to the nearest second.
ay D y r e s Ev r e b m Nu Number Strategies Order the numbers in each set from least to greatest. • 8.98, 9.89, 0.99, 0.89, 0.98 • 12.78, 12.87, 71.28, 17.82, 71.82 • 0.08, 1.01, 1.81, 0.8, 0.41
Many analog clocks show time in hours, minutes, and seconds. ➤ This clock shows a time of 4 hours 32 minutes 10 seconds. We write: 4 h 32 min 10 s In SI notation, we write: 04:32:10 ➤ One second is a very small unit of time. There are 60 seconds in one minute. It takes 60 s for the second hand to move all the way around the clock.
04:32:10
60 s = 1 min
Often, we do not need to tell time to the nearest second. We can round time to the nearest minute. There are 30 s in half a minute. When there are less than 30 s on the clock, round time back to the full minute.
About 09:57
When there are 30 s or more on the clock, round time forward to the next full minute.
About 05:18
➤ The circled date is October 24th, 2006. October is the 10th month of the year. In SI notation, we write: 2006 10 24
2006 10 24 195
1. Is each time estimate reasonable? Explain. a) Hop on one foot: 45 s b) Run all the way around the
schoolyard: 2 min 20 s 2. Write each date in SI notation. a) June 23, 1966
b) your birthday
c) the first day of next month
3. Write each date in words. a) 1994 07 16
b) 2000 01 01
c) 2004 11 09
d) 2026 03 31
4. Look at each clock.
In SI notation, write the exact time and the time to the nearest minute. a)
b)
c)
5. Jack estimated it would take 50 s to jog to his friend’s house.
When he left, his watch looked like this:
When he arrived, his watch looked like this:
a) How long did it take Jack to jog to his friend’s house? b) Was Jack’s estimate reasonable? Explain. c) Jack knocked at the door.
He waited 30 s before someone answered. What did his watch look like then? Draw it. d) His friend was not home. So, Jack jogged home. How long do you think it took him? Explain.
Tell about a day when knowing time to the nearest second was important. Tell about another day when it was not important to know the time to the nearest second.
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ASSESSMENT FOCUS
Question 5
L E S S O N
Exploring Time and Distance
You will need: • books to raise a ramp • a marble • Bristol board, 30 cm by 10 cm
• a metre stick • masking tape • a stopwatch
➤ Create a 10-cm high ramp. Use the Bristol board, books, and masking tape as shown. Mark distances of 2 m, 4 m, 6 m, and 8 m from the end of the ramp. ➤ One student lets the marble go at the top of the ramp. Another student measures the time the marble takes to travel 2 m. A third student records the time and distance in a table. ➤ Change roles. Repeat the steps. Measure the times for the marble to travel 4 m, 6 m, and 8 m. ➤ Look at the data in your table. What patterns do you see? Estimate the time the marble would take to travel each distance: 10 m, 12 m, 14 m
Marble Rolling Time (s)
Distance (cm)
Show and Share Compare your results with those of another group. Describe your strategy to estimate the times for the marble to travel 10 m, 12 m, and 14 m. How is the distance the marble travels related to the time it takes? LESSON FOCUS
Explore time and distance relationships.
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Speed is a measure of how fast an object is moving. ➤ Helen’s marble travels 50 cm every second. At this speed, it will go: 50 cm in 1 s 100 cm in 2 s 150 cm in 3 s 200 cm in 4 s, and so on. We can show this: • In a table
• On a graph
Time (s)
Distance (cm)
1
50
2
100
3
150
4
200
➤ Hannah’s marble travels 60 cm every second. Hannah’s marble goes farther each second than Helen’s marble. My marble moves faster than Helen’s marble.
➤ Colin’s marble travels 45 cm every second. Colin’s marble does not go as far each second as Hannah’s marble or Helen’s marble. My marble moves slower than Hannah’s marble and Helen’s marble.
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1. A toy car travels 5 cm every second.
At this speed, how far will it go in 1 s? 2 s? 3 s? 10 s? 2. A bowling alley is 25 m long.
The bowling ball travels 5 m in 1 s and 10 m in 2 s. The speed of the ball does not change. When will the ball hit the pins? Show your work. 3. A car travels 80 km in 1 h and 160 km in 2 h.
Suppose the car continues at the same speed. How long will it take to travel 400 km? Explain. 4. Campbell walks 80 m every minute.
Tyler walks 85 m every minute. a) How far will each person walk in 1 min? 5 min? 20 min? 1 h? b) Who is walking faster? How do you know? 5. a) When has Car A travelled 12 cm? b) When has Car B travelled 12 cm? c) Which car is moving faster? How do you know? 6. Alyssa swims 0.75 m every second.
Jillian swims 0.72 m every second. Which girl swims slower? How do you know? 7. The Cheung family plans to drive
500 km to a vacation resort. How long do you estimate the trip will take? Use pictures, numbers, and words to show your thinking.
y a D y r Eve s r e b Num Mental Math
Suppose you ride your bicycle down the road. Describe how the time you take and the distance you travel are related.
ASSESSMENT FOCUS
Question 7
Find the next number in each pattern. Write each pattern rule. • 1.2, 1.4, 1.6, 1.8, ! • 9000, 900, 90, 9, ! • 0.05, 0.5, 5, ! • 0.2, 0.9, 1.6, !
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