Video Transcript
Mason wants to meet his friends at
the park at 4 o’clock. It will take him 15 minutes to walk
there. What time does he need to leave his
house?
We know that Mason needs to be at
the park at 4 o’clock, and we know it takes him 15 minutes to walk there. We could use a number line to help
us solve this problem. We know that Mason needs to be at
the park by 4 o’clock. Let’s call this the end time. We also know that his walk will
take him 15 minutes. So, we need to use the number line
to find out what time it was 15 minutes ago. We need to count back 15
minutes.
We know that halfway between 3 and
4 o’clock, it’s 3:30. Halfway between 3:00 and 3:30 is
3:15. And halfway between 3:30 and 4
o’clock, it’s 3:45 or quarter to four. So, let’s start at 4 o’clock and
count back 15 minutes. Each of the smaller divisions on
our number line is worth five minutes. If we count back five minutes, that
will take us to 3:55 or five minutes to 4 o’clock. There are 60 minutes in an
hour. So, if we take away five minutes,
we’re at 3:55. If we count back five minutes from
3:55, that will take us to 3:50. Five minutes less than 3:50 is
3:45. So, Mason needs to leave his house
at 3:45.
We can check our answer using a
model of a clock. The minute hand started at number
12, and we had to count back 15 minutes or three lots of five: five, 10, 15. So, if Mason needs to meet his
friends at 4 o’clock and it takes him 15 minutes to walk to the park, he will need
to leave his house at 3:45.
