igsce maths modelling with directed numbers

1
modelling with directed numbers
application to real life situations
2
in this lesson
we use directed numbers to model real life
situations
identify situations that dont use directed
numbers
you get a chance to model some life situations
3
temperature
measured by a thermometer
400C
-50C
above freezing point

freezing point of water
below freezing point
4
time

4 BC
5 AD
4 BC
5 AD
5
directed numbers in business
my bank account 1
date Balance()
15/01/20 400 cr
16/01/20 100 dr
17/01/20 800 cr
400 in the bank account
- 100 in the bank account

800 in the bank account
cr
credit
()
dr
debit
(-)
negative balance
we owe the bank some money
we must pay the bank
(dangerous)
positive balance
the bank owes some money
(good)
the bank must pay us some money
6
directed numbers in business
my bank account 2
date Balance()
15/01/20 400
16/01/20 (100)
17/01/20 800
400 in the bank account
- 100 in the bank account

800 in the bank account
negative balances are shown in brackets
negative balance
we owe the bank some money
we must pay the bank
(dangerous)
positive balance
the bank owes some money
(good)
the bank must pay us some money
7
exercises
Japanese time is 9 hours ahead of Zimbabwean time
British time is 2 hours behind that of Zimbabwe.
Indias time is 3 hours behind that of Japan
Show the time zones on a number line
(use directed numbers to model the time zones)
8
answers
Japanese time is 9 hours ahead of Zimbabwean time
British time is 2 hours behind that of Zimbabwe.
Indias time is 3 hours behind that of Japan
Show the time zones on a number line
(use directed numbers to model the time zones)
Zimbabwe
India
Japan
Britain
there are many ways
zero is arbitrary
we choose where to start
9
answers
Japanese time is 9 hours ahead of Zimbabwean time
British time is 2 hours behind that of Zimbabwe.
Indias time is 3 hours behind that of Japan
Show the time zones on a number line
(use directed numbers to model the time zones)
Zimbabwe
Japan
India
Britain
there are many ways
zero is arbitrary
we choose where to start
10
exercises
Tashie, Linda, Rose and Muna are in a straight
line
Muna is 5 metres north of Tashie
Linda is 7 metres south of Muna
Rose is 4 metres south of Linda
Show their positions on a number line
(use directed numbers to model their positions)
11
answers
Tashie, Linda, Rose and Muna are in a straight
line
Muna
Muna is 5 metres north of Tashie
Linda is 7 metres south of Muna
Rose is 4 metres south of Linda
Show their positions on a number line
Tashie
(use directed numbers to model their positions)
Linda
there are many ways
zero is arbitrary
we choose where to start
Rose
12
answers
Tashie, Linda, Rose and Muna are in a straight
line
Muna
Muna is 5 metres north of Tashie
Linda is 7 metres south of Muna
Rose is 4 metres south of Linda
Show their positions on a number line
Tashie
(use directed numbers to model their positions)
Linda
there are many ways
zero is arbitrary
we choose where to start
Rose
13
exercises
At a company, work starts at 8.00am. On a certain
day
John arrived 7 minutes early for work.
Taku arrived 2 minutes when work had started
Rose arrived 4 minutes after Taku
Use directed numbers to model the arrival times
of the workers
14
answers
At a company, work starts at 8.00am. On a certain
day
John arrived 7 minutes early for work.
Taku arrived 2 minutes when work had started
Rose arrived 4 minutes after Taku
Use directed numbers to model the arrival times
of the workers
John
Rose
8.00am
Taku
there are many ways
zero is arbitrary
we choose where to start
15
answers
At a company, work starts at 8.00am. On a certain
day
John arrived 7 minutes early for work.
Taku arrived 2 minutes when work had started
Rose arrived 4 minutes after Taku
Use directed numbers to model the arrival times
of the workers
Rose
John
8.00am
Taku
there are many ways
zero is arbitrary
we choose where to start
16
where we can not use directed numbers
17
where we cannot use directed numbers
mass of a laptop
time taken to write a test
number of people in the class right now
in these cases
is absolute
0
we can not chose where to start from
number of people
18
summary
we saw where we can use directed numbers
temperature
time
business
we saw where we can not use directed numbers
mass of iPhone
number of people in a room right now
time to do a task
you also did exercises modelling life situations
19
more free maths lessons
at
igscemaths24.thinkific.com
20
golf?