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Age Dependency Ratios: Numbers in Context

Eric Gaze
Alfred University
Writing Assignment for MATH 101: Communicating with Numbers
Author Profile
This material was originally developed by the the National Numeracy Network
as part of its collaboration with the SERC Pedagogic Service.


Unreviewed Activity submitted in preparation for the NNN Writing with Numbers Workshop

In this writing assignment students are introduced to the concept of age dependency ratios. Students will first compute these ratios for the United States and interpret them by using them in informative sentences. Using future population estimates, students can recompute these ratios and reflect on possible consequences of the aging of the American population. The same ratios are computed for Ireland and for a Third World country providing relative context for the US numbers.

Learning Goals

  • Students will reinforce computation skills related to ratios and percentages.
  • Students will interpret numbers in context.
  • Students will reflect on why certain numbers are computed and how social issues such as the "aging of America" can be quantified.
  • Students will explore data sets on the internet.
  • Students will use numbers to help compare first and third world countries.

Context for Use

This assignment is for an introductory Math for the Liberal Arts course, called Communicating with Numbers, which introduces students to the concept of quantitative literacy. The relevance of quantitative information for engaged citizenship is explored as well as the core numeracy skills required. I anticipate assigning one writing assignment such as this per week.

Description and Teaching Materials

Assignment Handout (Microsoft Word 34kB May16 08)

Teaching Notes and Tips

This handout uses the definition of dependency ratios as given on the Census website. These definitions effectively compute these ratios as percentages but do not say so and even more confusing these are part to part ratios making the percentages more difficult to interpret.


I will grade each of the eleven questions for computational correctness and for ability to articulate the relevance of numbers in context. I will grade each question on a 9 point scale:
Meets all criteria at high level, clear and easy to follow: 9 8 7
Meets some criteria, some lapses in clarity or development: 6 5 4
Meets few criteria, unclear or undeveloped: 3 2 1 0

References and Resources