Subtraction fun

Subtraction fun

Auto-markingPencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about working out word problems.

Question 1Change answer

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a)  i)  Ava had 4 crackers.
         She ate 3 crackers.
          How many crackers were left?  
 

Question 1Change answer

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     ii)  Anesi had 5 strawberries.
          He ate none of the strawberries.
          How many strawberries were left?  
 

Question 1Change answer

kete -pinecones.jpg
b)  i)   Rangi had 4 pine cones in her kete.
           She gave some away.
           There is 1 pine cone left.
           How many pine cones did she give away? 
 

Question 1Change answer

kete - seashells.jpg
      ii) Petra had 3 shells in her kete.
          She gave some shells away.
          There is 1 shell left.
          How many shells did she give away?  
 

Question 1Change answer

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c)  i)   This box has some blocks in it.
          Sam took out 2 blocks.
          There are 2 blocks left in the box.
          How many blocks were in the box to start with?  
 

Question 1Change answer

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     ii)  This box has some balls in it.
           Heath took out 4 balls.
           There is 1 ball left in the box. 
           How many balls were in the box to start with?  
Task administration: 
This task can be completed online or with pencil and paper. If completed online, auto-marking will be displayed to students.
Level:
1
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
subtraction
Description of task: 
This task is about subtracting with different parts of the equation missing.
Curriculum Links: 
This resource can be used to help to identify students' achievement levels for adding and subtracting whole numbers.
Links to Numeracy Professional Development Projects
Book 5: Teaching Addition, Subtraction, and Place Value: pages 17-20 (moving students from one-to-one counting to counting from one on materials or imaging).
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Additive thinking, sets 1-4
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
    Y2/3 (03/2017)
a)  i)
     ii)
1
5
very easy
very easy
b)  i)
     ii)
3
2
very easy
very easy
c)  i)
     ii)
4
5
very easy
easy
Based on an online sample of 25 students
Teaching and learning: 
This resource uses three different problem types - Result unknown, Change unknown, and Start unknown as outlined on page 8 of The Numeracy Professional Development Project's Book 5: Teaching Addition, Subtraction, and Place Value (2012 edition).

All numbers used are between 0 and 5.

Diagnostic and formative information: 
  Common error Likely reason
b) i)
    ii)
1
1
 Gives the remainder rather than solving the subtraction question 4 - ? = 1 or 3 - ?  = 1

 
c) i)
    ii)
2
4
Gives the number of visible items rather than the starting amount.
c) ii)
3
 Calculates 4 - 1 rather than ? - 4 = 1
Next steps: 
First, check that students have read the question carefully.
If necessary, have students work in pairs, reading the question together and recording how to solve the problem by using materials, symbols, images or a number sentence.
Students can practise this skill with a range of word problems without needing to solve them.
Alternatively, in small groups or as a class, read out a word problem.  Have students hold up the correct operator needed to solve the problem (+, – initially, moving on to x and ÷ as appropriate).
 
Use materials to 'act out' the scenarios provided, and/or other similar scenarios.
Use a bag or box and model parts b) and c) with students.  Use up to five items in total to start with, until students have explored with materials and consolidated their understanding of Change unknown and Start unknown.
Provide pairs of students with bags or boxes in which to place an unknown number of items which can then be removed or given away.  Have the students record their problems and how they solved them.
 
 
For students who are comfortable working with numbers below 6, try these ARB resources which use larger numbers:
For more information on different forms of subtraction number sentences and strategies for solving subtraction problems, see the Addition and Subtraction Concept Map