Watch It! Elapsed Time Clock EI-1724 Anleitung Seite 4

Subtracting Time—What Time Did the Event Start?
Calculating a Past Event Time
Pose a question such as, The party ended at 3:00
did the party begin?
To solve, set both the START and END watches to
3:00 . .
p m
Next, open the ELAPSED TIME stopwatch window
door. It should read 0:00 because both watches are
currently set to the same time.
While watching the ELAPSED TIME window, move the
minute hand on the START watch counterclockwise
until the ELAPSED TIME window reads 4 hours (4:00).
What time does the START watch read now? (11:00
That is the time the party started.
Telling Time
You can use the Elapsed Time Clock to practice telling time with your students.
Simply use one of the watches and its associated digital window below. (Leave
the Elapsed Time door closed and ignore the second watch for this activity.)
Ask your students to identify the color of the hour hand (blue) and minute hand
(red). Move the hands to display a time (e.g., 1:00) and ask the students to watch
the time displayed in the digital window below. Discuss where the hands are
pointing (e.g., the hour hand is pointing to the 1 and the minute hand is pointing
to the 12).
4.
. . It lasted 4 hours. What time
p m
. .)
a m
Figure 10
Figure 11