Comparison: It Helps Students Learn to Estimate

Estimation: we do it all the time. Whether it is approximating how much we owe for our share of pizza or how many people can fit safely in an elevator, estimation occurs daily. In an article by Star, Kenyon, Joiner and Rittle-Johnson (2010), a group of fifth and sixth students sharpened their understanding of estimation by comparing three different methods.


The Study
Just over 150 study participated in the study. Half were assigned to a group that were taught the different methods of estimation sequentially; the remaining students were taught the same three methods by means of comparison. In this second group, students were encouraged to judge how effectively each method was at approximating the real answer. They were also asked their opinion as to which method was easiest to compute.
Students in both groups were given the same pre-test, post-test, and a follow-up two weeks later. While students in both groups showed comparable improvement in conceptual understanding, the group asked to compare methods was more comfortable in their use of the three different methods. They also demonstrated better retention two-weeks later, suggesting that conceptual understanding paired with versatility results in better long-term recall.

My Future Teaching
With study in mind, I will be sure to include opportunities for my students to defend, compare and contrast various mathematical procedures. This will not only deepen their conceptual understanding, but also ensure they are versatile in multiple means of problem solving. These two things combined will support better long term retention, increasing the odds that when real life asks them to estimate, they'll know how and why.

Citation: 
Star, J. R., Kenyon, M., Joiner, R. M. and Rittle-Johnson, B. (2010). Comparison helps students learn to       be better estimators. Teaching children mathematics 16 (9), 557-563.