Making number sentences

Making number sentences

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about writing and solving number sentences.
illustration: selection of number sentences

A number sentence uses numbers and symbols instead of words.

For example, a story problem is:

Tamatea has 12 marbles, and Bob has 9 marbles. How many marbles do they have altogether? 

and 12 + 9 = ? is a number sentence.

Question 1Change answer

a)  Shane got 9 shellfish, Tane got 4 shellfish, and Rahera got 7 shellfish.
     Write a number sentence to show how many shellfish they got altogether.

Question 1Change answer

b) Jake ran for 3 hours on Monday, 2 hours on Tuesday, and 5 hours on Wednesday. 
    Write a number sentence for how many hours he ran altogether over the 3 days.

Question 1Change answer

c)  Leilani had 15 chocolate bars. She gave 2 to her sister, 4 to her brother, and 1 each to her mother and father. 
     Write a number sentence to show what happened to the chocolate bars.

Question 1Change answer

d) Write a story problem for the number sentence: 8 + 6 + 4 = 18.
Task administration: 
This task is completed with pencil and paper or online.
Level:
2
Curriculum info: 
Maths, Number and Algebra, Equations and expressions
Key Competencies: 
Using language, symbols, and texts
Keywords: 
number sentences, arithmetic operations, story problems
Description of task: 
Students create and solve number sentences that represent story problems.
Curriculum Links: 
Key competencies
This resource involves writing a word problem that corresponds to a given number sentence. This relates to the Key Competency: Using language, symbols and text.

For more information see http://nzcurriculum.tki.org.nz/The-New-Zealand-Curriculum/Key-competencies

Learning Progression Frameworks
This resource can provide evidence of learning associated with
Using symbols and expressions to think mathematically, set 3
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 

 

Y5 (05/2005)

a)

9 + 4 + 7 = 20
[Accept correct equation with no solution.]

very easy

b)

3 + 2 + 5 = 10
[Accept correct equation with no solution.]

easy

c)

15 - 2 - 4 - 1 - 1 = 7
[Accept correct equation with no solution.]

easy

d)

Any story problem that incorporates adding the numbers 8, 6, and 4.

easy

These results are based on a trial set of 149 Y5 students.

Teaching and learning: 
This resource is concerned with showing how abstract mathematical equations (number sentences) can represent real-life relationships (story problems).
Diagnostic and formative information: 
  Common error Likely calculation Likely misconception
a)
b)
c)		 20
10
7		 9 + 4 + 7
3 + 2 + 5
15 - 2 - 4 - 1 - 1		 Students solve the equation without writing a number sentence.
c) 23 15 + 2 + 4 + 1 + 1 Incorrect interpretation of "gave away".
Next steps: 
Students who show only the solution may not be aware of the importance of showing the processes they go through to find those solutions. Encourage students to record all their workings. Students who are comfortable with addition and subtraction relationships could create and solve number sentences involving multiplication and/or division.