Download Shining Add 3 Fractions Session plans

Addition 3
Fractions
Objectives

Add pairs of fractions with related denominators

Add pairs of fractions with unrelated denominators using ‘smile
and kiss’
For this unit you will need:
1-10 number cards (see resources)
Watch out for pupils who:

add the denominators and numerators to add pairs of fractions
(rather like multiplying the numerators and denominators to
multiply pairs of fractions);

struggle to convert both fractions to ones with the same
denominator because their understanding of equivalence is shaky;

think that when the numerator and denominator are multiplied by
the same number, that the result is a bigger fraction.
HSNP © Hamilton 2013
Shining Term 2
Addition 3
Session 1
Objective: Add pairs of fractions with related denominators
Teacher input with whole class
 Write the following additions on the board and ask pupils to discuss in
pairs how they would solve each:
1
/2 + 1/4, 5/6 + 2/3, 3/5 + 7/10, 5/9 + 1/3
 Draw out that we cannot add the pairs of fractions as they have
different denominators so first we need to change them so both have
the same denominator. So in the first we can change both fractions to
quarters, in the second change both to sixths, in the third change both
to tenths and the fourth change both to ninths.
 Ask pupils to work in pairs to do this, and find the totals. Explain that
some will give an improper fraction as an answer. So their work is still
not done as they should then convert the answer to a mixed number!
 Take feedback.
Paired pupil work
 Pupils work in pairs to draw a pyramid of boxes, beginning with three
on the bottom row. They write 1/2, 5/8 and 3/4 in the bottom row.
They add neighbouring fractions and write the answer in the box that
overlaps the pair of numbers. They continue up the pyramid until they
reach a total at the top, e.g.
20
9
1
/2


/8
Simplify to 5/2, then
convert to 2½
11
/8
/8
5
/8
3
/4
Repeat with fractions 1/2, 5/6 and 1/12 in the bottom row.
Take feedback.
HSNP © Hamilton 2013
Shining Term 2
Addition 3
Session 2
Objective: Add pairs of fractions with unrelated denominators using ‘smile
and kiss’
Teacher input with whole class
 Write 2/3 + 3/4 on the board and ask pupils to discuss in pairs how they
would solve it. Take feedback. Agree that we need to convert both
fractions to the ones with the same denominator. Discuss what
fraction we could convert them to. We are looking for a number that
both 3 and 4 will go into. Draw out that we could convert them both to
1
/12s, i.e. find the equivalent numbers of twelfths. Ask pupils to do this,
and then convert 3/4 to twelfths. They then find the total.
 Show (or remind) pupils that there is way to remember how to do this
called ‘smile and kiss’. Draw the following on the board:
12


3
5
3
4
15
Talk through the steps: multiply the denominators together (smile)
multiply 3 by 4, and 5 by 3 (kiss) then add these together to get 27/20.
Ask pupils to discuss in pairs why this works. Take feedback. Agree we
are changing each fraction into 20ths by multiplying the denominators.
3
+
3
5
4
= 12 + 15
20
= 27
20
Ask pupils to convert 27/20 to a mixed number.
Paired pupil work
 Pupils use ‘smile and kiss’ to add 2/5 + 2/3, 1/4 + 1/3, 2/7 + 2/3 and
three other pairs of fractions of their choice. Remind them to convert
to mixed numbers and simplify the answer where possible.
HSNP © Hamilton 2013
Shining Term 2
Addition 3
Session 3
Objective: Add pairs of fractions with unrelated denominators using ‘smile
and kiss’
Teacher input with whole class
 Write 1/6 + 3/4 on the board. We can work this out using ‘smile and
kiss’. But you might also spot that rather than converting both to 1/24s
we could convert both to 1/12s.
 Ask half the class to use 'smile and kiss’ to find the answer, and the
other half to convert both fractions to 1/12s, then add them. Point out
that both ways give the same answer. The ‘smile and kiss’ group can
simplify their answer at the end to give 11/12.
Paired pupil work
 Ask pupils to work in pairs to either spot a common multiple of the
denominator and both fractions, or use smile and kiss’. 7/10 + 3/4; 3/8 +
5
/6; 5/6 + 4/9.
Teacher input with whole class
 Take feedback on which way pupils found easier.
Paired pupil work
 Pupils shuffle a set of 1 to 10 number cards (see resources), and place
upside down. They take the top four and use in any order they like to
make two fractions both less than 1. They add the two fractions
together. If the answer is less than 1, they score 1 point. If the answer
is greater than 1 they score 2 points.
 They carry on adding pairs of fractions until you ask them to stop. Did
any pair score more than 20 points?
HSNP © Hamilton 2013
Shining Term 1