You have a job, but… Do you know rule of 3?

You have a job, but… Do you know rule of 3?

Javier Luque 16 junio 2015 Comments

A few days ago, while looking at some job offers in a local newspaper, an ad caught my attention. A position as a business adviser in micro finance required applicants to have completed secondary education and be able to master two independent set of skills: basic math operations, including the rule of three, and socio-emotional skills management (be proactive, work under pressure, among others). While a teenager with a high school education should master these skills, the fact that the ad specifically mentioned it made me think about whether graduates really know how to apply them.

Most recent discussions focus on how socio-emotional skills are important to perform successfully in the labor market rather than discussing the relevance of cognitive, particularly math skills. This ad requires for candidates to master the rule of three, which is a topic usually taught in the final years of primary education and is key to apply arithmetic concepts in our daily lives. Do teenagers in the region know how to use the rule of three? My concern was resolved, at least partially, when I found a question in the PISA test applied in 2012, which required students to use the rule of three. The question was:


The Gotemba road to climb Mount Fuji is 9 km long. Toshi estimates that he can walk to the top of the mountain in a average of 1.5 kilometers per hour, and return at twice the speed.Climbers must return from a walk of 18 km at 8 pm. These rates take into account meals and time to rest.

Using Toshi’s speed, what is the latest time he can leave to return at 8 pm?

Very few students in the region answered correctly this question. For example, in the case of Peru, only 5% of the girls and 8% of the boys got it correct.

Clearly, most of the boys in the region would not be able to apply to this position. And an obvious follow up question is what other positions would not they be able to apply to? Probably to a lot, given that there is a relationship between mathematical knowledge and the skills required to perform well in many occupations. A fun and relatively less known book, written by Hal Saunders gives us a look at the relationship between occupations and mathematical knowledge. (When Are We Ever Gonna Have To Use This?) Saunders analysis of ratios and proportions (where the concept of rule of three is included) signals that the rule is required in 80 percent of the occupations presented.

As a final reflection, although we already knew the relationship between the PISA test scores and the countries long-term growth, the newspaper ad brings us down and makes us see specific problems in basic concepts. The challenges in identifying candidates with correct emotional skills has already been documented. However, it is necessary to complement this analysis with cognitive skills, so that the education system can clearly support the process of economic growth.

    One thought on “You have a job, but… Do you know rule of 3?

    1. HelenHe@IWB

      Thank you for sharing the book.

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