some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the...

22
some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities look at/for alternative methods

Upload: homer-townsend

Post on 05-Jan-2016

212 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

some (quick) ways to (probably) make consolidation tasks at least a bit more interesting

• reverse the question• greater generality • seek (exhaust) all possibilities• look at/for alternative methods

Page 2: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

solve 3x – 4 = 20 make up some equations with a solution of x = 8: make them as complicated as you can

what integer solutions can you find to 3x – 4y = 20?

what numbers must ‘n’ be for 3x – n = 20 to have an integer solution?

in trying to solve 3x – 4 = 20, what happens if you divide everything by 3 first?

Page 3: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

what are the coordinates of the mid-point between (2 , 1) and (6, 9)?

which pairs of points have (4, 5) as a mid-point?

if (4, 5) is one third of the way along a line what could the two end-points be?

what other integer points lie on the line joining (2, 1) to (6, 9)?

can you find two (or more) ways to find the mid-point between two points?

Page 4: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

find several two, 2-digit subtraction sums with an answer of 7

find all the (positive) options for the result of a subtraction sum using the digits 6, 7, 8 and 9 (without repeats)

what general properties do the digits in a two, 2-digit subtraction sum, AB – CD have if the result is 7?

what is 86 – 79?

how can you see that the result of the sum 86 – 79 must be 7 by relating the numbers to multiples of 7?

Page 5: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

what is the mean average of 0 , 3 and 15?

give sets of three numbers with a mean of 6

can the mean be smaller than the median for a set of three integers?

find all integer sets of 4 numbers with a mean of 6 and a range of 6

can you think of (another) way to find the mean of 138, 142, 135, 148 and 137?

Page 6: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

the rectangle is reflected and ends up at (1, – 2), (5, – 2), (1, – 4) and (5, – 4) what is the mirror line’s equation?

what happens to the coordinates of a shape when you reflect it in y = x?

what happens to the four corner coordinates when the shape is reflected in y = x + 1?

can you use a rotation followed by a reflection that has the same effect as reflecting in y = x?

reflect the rectangle in the line y = x

Page 7: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities
Page 8: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

Simpsons

0

20

40

60

80

100

120

140

160

180

200

0 10 20 30 40 50 60 70 80

age years

hei

gh

t cm

Bart

Homer

Marge

Maggie

Lisa

Abraham

Mr Burns

Simpsons

Thanks to the Shell Centre

Page 9: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

a large bag of flour weighs 24kgit costs £21.50

a sponge cake uses 150g of this flour

what are the questions that these calculations find out?

24000150

2421.50

215024

21.5024000

× 150 (a) (b) (c) (d)

Page 10: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

3 7 6 1 5

3 2 5 ?

? H: L:26

46

? H: L:35

25

H: L:

H: L:

play your cards rightthe numbers 0 to 9 are arranged randomly probability of

H = higherL = lower

0 1 23 4 56 7 89

?

0 1 23 4 56 7 89

Page 11: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

can you suggest

some subtraction sums with an answer – 5 ?

an experiment where the probability is ¾ ?

two coordinate pairs with a gradient of ½ between them ?

a quadrilateral whose diagonals cut at 90o ?

two numbers with a highest common factor of 15 ?

a hexagon with rotational but no line symmetry ?

numbers that might round to 350 ?

numbers with exactly five factors ?

the dimensions of a cuboid with a volume of 24 cm3 ?

a ratio question with an answer £180 and £240?

Page 12: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

Egyptian fractions

the Ancient Egyptians only used unit numerator fractions

they turned other fractions into sums of two or more fractions, all with a numerator of 1

(apart from ⅔)

they used fractions with different denominators

Page 13: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

112

Egyptianfractions

Ancient Egyptians turned fractions into a sum of fractions with unit numerators

can you find other ways to represent these two fractions in this ‘Egyptian’ way?

118

+5

36=

116

120

+9

80=

Page 14: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

one way to do this

is to split up the numerator into a sum

so that the two numbers are both factors of the

denominator

so that they cancel…

436

136

+5

36=

536

19

136

+5

36=

Egyptianfractions

Page 15: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

sometimes you cannot do this straight away

so, look at an equivalent fraction

until you can find two (or more) numbers that are both factors

of the denominator

which cancel…

728

128

+8

28=

27

14

128

+27

=

Egyptianfractions

remember that the denominators must be different

Page 16: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

try to make this out of two unit fractions

and another way

512

512

try to make this out of two unit fractions

and another way

712

712

1112

why does this need three unit fractions?

try to find two ways to do this

Egyptianfractions

Page 17: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

49

215

1021

59

1118

713

(1)

(2)

(3)

(4)

(5)

(6)

(7)

try to write these as the sum of two fractions with numerator 1 and different denominators, as the Ancient Egyptians did

29

25

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15) 38

find two ways for

(16) find two ways for3

10

(17) find three ways to writeas the sum of two unitary fractions, with different denominators

18

(18) find three ways to writeas the sum of two unitary fractions, with different denominators

110

find four ways to writeas the sum of two unitary fractions, with different denominators

(19)2

15

(20)

720

514

950

623

find three ways to writeas the sum of three unitary fractions, with different denominators

45

449

Egyptian fractions

1124

Page 18: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

27 4

19

823

2135

21

harder

Egyptian fractions

try to write these as the sum of two unit fractions

they can all be done

Page 19: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

1

4

1

28+

2

7=

1

5

1

95+

4

19=

1

3

1

69+

8

23=

1

7

1

91+

2

13=

answers

1

6

1

14+

5

21=

Page 20: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

16

1??

+211

=

13

133

+?11

=

1?

1??

+311

=

1?

1??

+611

=

112

1???

+111

=

Egyptian fractions

some of the ‘elevenths’family

why/how do these work in this way?

Page 21: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

15

120

+1?

=

18

156

+1?

=

1?

1??

+13

=

1?

1??

+1

10=

1?

1??

+16

=

Egyptian fractions

Egyptian fractions sum to another Egyptian fraction

what is a general rule for these?

Page 22: Some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the question greater generality seek (exhaust) all possibilities

1n

1n(n – 1)

+1?

=substitute some numbers for ‘n’what happens?try to prove that this will always work

2n + 1

2n(n + 1)

+2n

=substitute some odd numbers for ‘n’what happens?

2n + 2

4n(n + 2)

+2n

=substitute some even numbers for ‘n’what happens?

what do these last two statements establish?