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Pickups 2010 Fractional Thinking


Pickups 2010 Fractional Thinking Lisa Heap, Jill Smythe & Alison Howard Numeracy Facilitators – PowerPoint PPT presentation

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Title: Pickups 2010 Fractional Thinking

Pickups 2010Fractional Thinking
  • Lisa Heap, Jill Smythe Alison Howard
  • Numeracy Facilitators

Pirate Problem
  • While you are waiting
  • Three pirates have some treasure to share. They
    decide to sleep and share it equally in the
  • One pirate got up at at 1.00am and took 1/3 of
    the treasure.
  • The second pirate woke at 3.00am and took 1/3 of
    the treasure.
  • The last pirate got up at 7.00am and took the
    rest of the treasure.
  • Do they each get an equal share of the treasure?
  • If not, how much do they each get?

The Rope Activity
  • Identify the progressive strategy stages of
    fractions, proportions and ratios.
  • Further develop teachers confidence and content
    knowledge of fractions.
  • Explore key ideas, equipment and activities used
    to teach fraction knowledge and strategy.

The 4 Stages of the P.D Journey
Organisation Organising routines, resources etc.
Focus on Content Familiarisation with books,
teaching model etc.
Focus on the Student Move away from what you are
doing to noticing what the student is doing
Reacting to the Student Interpret and respond to
what the student is doing
Developing Proportional Thinking
  • A chance to recap what needs to be taught at the
    different stages.
  • Decide which strategy stage fits each scenario.
  • Use the number framework to help you.
  • Highlight all the fractional knowledge across the
    stages (pg18-22).

Fraction Knowledge Test
  • Draw 2 pictures (a) one half (b) one eighth
  • Mark 5 halves on a number line from 1-5
  • 12 is three fifths of what number?
  • What is 3 5?
  • Draw a picture of 7 thirds
  • Write one half as a ratio.
  • The ratio of kidney beans to green is 34. What
    fraction of the beans are green?
  • Order these fractions
  • 2/4, 3/4, 2/5, 7/16, 2/3,
  • Now include these and decimals into your
  • 30, 75, 0.38, 0.5

Morning Tea
  • After morning tea we will split again
  • Stages 1, 2, 3 with Alison
  • Stages 4 8 with Jill and Lisa

Body Fractions
  • In the rectangle below, what is the ratio of
    green to blue cubes?
  • What is the fraction of blue and green cubes?
  • Can you make another structure with the same
    ratio? What would it look like?
  • What confusions may children have here?

More on Ratios.
  • Divide a rectangle up so that the ratio of its
    blue to green parts is 73.
  • Think of other ways that you can do it.
  • What is the fraction of each colour?
  • If I had 60 cubes how many of them will be of
    each colour?

A Ratio Problem to Solve
  • There are 27 pieces of fruit. The ratio of fruit
    that I get to the fruit that you get is 27. How
    many pieces do I get?
  • How many pieces would there have to be for me to
    get 8 pieces of fruit?
  • What key mathematical knowledge is required here?

What about this?
  • Two students are measuring the height of the
    plants their class is growing.
  • Plant A is 6 counters high.
  • Plant B is 9 counters high.
  • When they measure the plants using paper clips
    they find that Plant A is 4 paper clips high.
  • What is the height of Plant B in paper clips ?
  • Consider..
  • Scott thinks Plant B is 7 paper clips high.
  • Wendy thinks Plant B is 6 paper clips high.
  • Who is correct?
  • What is the possible reasoning behind each of
  • answers?
  • How would you further support Scotts thinking?

Key Idea
  • The key to proportional thinking is to be able to
    see combinations of factors within numbers.
  • Wendy is correct, Plant B is 6 paper clips high.
  • Scotts reasoning To find Plant Bs height you
    add 3 to the height of Plant A 4 3 7.
  • Wendys reasoning
  • Plant B is one and a half times taller than Plant
    A 4 x 1.5 6.
  • The ratio of heights will remain constant. 69 is
    equivalent to 46.
  • 3 counters are the same height as 2 paper clips.
    There are 3 lots of 3 counters in plant B,
    therefore 3 x 2 6 paper clips.

Exploring Book 7
  • Stage 4-5
  • Fraction Circles (page 20)
  • Stage 5-6
  • Birthday Cakes (page 26)
  • Stage 6-7
  • Hot Shots (page 46)

Welcome Back Alisons Group
Views of Fractions
  • What does this fraction mean?

3 7
3 out of 7
3 7
3 over 7
3 sevenths
The Problem with Language
Use words first before using the symbols e.g.
one half not 1 out or 2 How do you explain the
top and bottom numbers? 1 2
The number of parts chosen The number of equal
parts the whole has been divided into
Continuous Model
  • Models where the object can be divided in any way
    that is chosen.
  • e.g. ¾ of this line and this square are blue.

Discrete Model
  • Discrete Made up of individual objects.
  • e.g. ¾ of this set is blue

Whole to Part
  • Most fraction problems are about giving students
    the whole and asking them to find parts.
  • Show me ¼ of this circle?

Part to Whole
  • We also need to give them part to whole problems,
  • ¼ of a number is 5.
  • What is the number?

Teaching Fractions
  • What do you see as some of the confusions
    associated with the teaching and understanding
  • of fractions?

Misconceptions with Fractions
  • Charlotte believes that one eighth is bigger than
    one half.
  • 1/2 ? 1/3 ? 1/4 ? 1/8
  • Why do you think Charlotte has this
  • How would you address this misconception?
  • What equipment would you use?

Misconceptions with Fractions
  • Fiona says the following
  • ¼ ¼ ¼ 3/12
  • Why do you think Fiona has this misunderstanding?
  • How would you address this misconception?
  • What equipment would you use?

Misconceptions with Fractions
  • A group of students are investigating the books
    they have in their homes.
  • Steve notices that of the books in his house
    are fiction books, while Andrew finds that of
    the books his family owns are fiction.
  • Steve states that his family has more fiction
    books than Andrews.
  • Consider.
  • Is Steve necessarily correct?
  • Why/Why not?
  • What action, if any, do you take?

Key Idea
  • The size of the fraction depends on the size of
    the whole.
  • Steve is not necessarily correct because the
    amount of books that each fraction represents is
    dependent on the number of books each family
  • For example of 30 is less than of 100.
  • Key is to always refer to the whole. This will
    be dependent on the problem!

Misconceptions with Fractions
  • Heather says is not possible as a fraction.
  • Consider..
  • Is possible as a fraction?
  • Why does Heather say this?
  • What action, if any, do you take?

Key Idea
  • A fraction can represent more than one whole.
  • Can be illustrated through the use of materials
    and diagrams.
  • Question students to develop understanding
  • Show me 2 thirds, 3, thirds, 4 thirds
  • How many thirds in one whole? two wholes?
  • How many wholes can we make with 7 thirds?

What could be the misconception here?
  • 2 chocolate bars shared amongst 5 students
  • What does each student get?

  • Because the divisor is 5 the natural denominator
    is fifths. Each bar is broken into five equal
  • One way of solving the problem is to give each
    student one piece from each bar. Each will have
    2 pieces. Compared with one bar each student has
    2 fifths of a bar.
  • The common error here is for students to think
    the answer is 2/10 because they think the answer
    is 2 out of 10.

Misconceptions with Fractions
  • You observe the following equation in Bills
  • Consider..
  • Is Bill correct?
  • What is the possible reasoning behind his
  • What, if any, is the key understanding he needs
    to develop in order to solve this problem?

Key Idea
  • To divide the number A by the number B is to find
    out how many lots of B are in A. When dividing
    by some unit fractions the answer gets bigger!
  • No he is not correct. The correct equation is
  • Possible reasoning behind his answer
  • 1/2 of 2 1/2 is 1 1/4.
  • He is dividing by 2.
  • He is multiplying by 1/2.
  • He reasons that division makes smaller
    therefore the answer must be smaller
  • than 2 1/2.

Misconceptions with Fractions
  • When you multiply by some fractions the answer
    gets smaller
  • 1/4 x 1/3 1/12
  • This is ? of one whole strip.
  • If it is cut into quarters, four equivalent
    pieces, what will each new piece be called?

Fractions Video
  • What was the key purpose of the lesson?
  • What key mathematical language was being
  • How did materials/equipment support the
    childrens learning? What may have happened if
    the equipment was not present?
  • Why did the teacher use the example 101/4 in the
  • In terms of the teaching model, where do you
    think the children are at?
  • What would be you next step with this group of

Summary of key ideas
  • Fraction language - emphasise the ths code
  • Fraction symbols use symbols with caution,
    start with words
  • Continuous and discrete models - use both
  • Go from Part-to-Whole as well as Whole-to-Part
  • Fractions are numbers and operators
  • Fractions are a context for add/sub and mult/div
  • Fractions are always relative to the whole and
    the whole can be bigger than one.

Thought for the day
  • Smart people believe only half of what they hear.
  • Smarter people know which half to believe.
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