City populations

City populations

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 adding and subtracting decimal numbers.

Question 1Change answer

new-jersey-skyline-hi.png

a)  The population of a city went up from 1.83 million to 2.54 million. 

     What was the population increase?

Question 1Change answer

city

b)  In another city the population went down from 1.72 million to 1.39 million. 

     What was the population decrease?

Question 1Change answer

c)  Before the population changes, what was the total population of the two cities?

     

Task administration: 
This task can be completed with pencil and paper or online (with auto-marking displayed to students).
Levels:
3, 4
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
decimals, addition, subtraction
Description of task: 
Students calculate addition and subtraction problems, written in decimal form, for city populations.
Curriculum Links: 
 
This resource can help to identify students' ability to apply additive and simple multiplicative ideas flexibly to combine or partition numbers to solve decimal addition and subtraction problems.
 
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Additive thinking, sets 6-7
Additive thinking, sets 7-8
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
 

Y6 (06/1997)

Y7 (06/1997)
a) 0.71 million [Accept 710 000] difficult difficult
b) 0.33 million [Accept 330 000] very difficult difficult
c) 3.55 million [Accept 3 550 000] difficult difficult
Diagnostic and formative information: 
  Common error Calculation Likely reason
a)b) 4.37 million3.11 million 1.83 + 2.541.72 + 1.39 Adding rather than subtracting.
a)-c) wrong magnitude, e.g., a) = 71 million    
c) a) + b)   Lacks comprehension of arithmetic operation to use on what amounts.