some (quick) ways to (probably) make consolidation tasks at least a bit more interesting reverse the...
TRANSCRIPT
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
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?
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?
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?
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?
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
Simpsons
0
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80
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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
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)
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
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?
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
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=
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
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
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
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
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
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=
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?
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?
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?