Sunday, June 30, 2013

The Curse of Rote Teaching [PEMDAS & its Siblings]

An excellent question was raised in the Global Math Department bulletin board that I decided to elaborate upon in here.

Rote teaching of certain mathematical rules and the lack of understanding of their underlying concepts lead to difficulties that students will continue to struggle with even at higher level courses such Precalculus, College Algebra, and even Calculus. These difficulties manifest themselves in what I have called MBs in an earlier post

In this post, I will address an MB related to PEMDAS. So, what to make of a student's treatment of let's say 4-6(3x+1) the same way as -2(3x+1)? And, generally how do we disrupt the misconception inertia that PEMDAS and its siblings of rote-taught mathematical rules engender within our students?

1) Geometry, Geometry, & Geometry: I am a firm believer that Geometry should be used as extensively as possible to enable our students grasp algebraic concepts better and at a deeper level for geometric, graphical, and pictorial representations offer visual clues and cues that facilitate students' understanding of abstract concepts of Algebra and other mathematical fields. So, have the students predict the nature of the graphs associated with the above two expressions and then have them execute the actual graphing processes either by hand or with a graphing technology tool (to add potential "What if?" investigations afterwards.) 

Once the above tasks are completed, one must ask the students to interpret the outcomes, reflect upon them, and tie them to other math concepts (such as translation, scaling, and meaning of slopes to mention a few) to complete the learning cycle. What other geometric tools have you used to aid your students' understanding of mathematical concepts?

2) Carefully crafted assessment items can also aid our students in confronting their misconceptions and try to sort out the difficulties therein until they get a strong handle on the underlying concepts. Following is such an assessment item.

*** Start of Assessment Item ***

PEMDAS refers to the concept of order of operations. Four students argued about how PEMDAS should be carried out when evaluating mathematical expressions. To find the answer to "1 – 10 ÷ 5 ∙ 2 + 44 = x, what is x?" the students used the four different steps shown below. Which of the four solutions steps do you agree with and why? Make sure you state how the student of your choice must have interpreted PEMDAS based on his/her solution steps.

Student 1 Solution: 1 – 10 ÷ 5 ∙ 2 + 44 = 45 – 10 ÷ 5 ∙ 2 = 35 ÷ 5 ∙ 2 = 7 ∙ 2 = 14
Student 2 Solution: 1 – 10 ÷ 5 ∙ 2 + 44 = -9 ÷ 10 + 44 = -0.9 + 44 = 43.1
Student 3 Solution: 1 – 10 ÷ 5 ∙ 2 + 44 = 1 – 2 ∙ 2 + 44 = 1 – 4 + 44 = 41
Student 4 Solution: 1 – 10 ÷ 5 ∙ 2 + 44 = 1 – 10 ÷ 10 + 44 = 1 – 1 + 44 = 44

*** End of Assessment Item ***

With such assessment items both the student as well as the instructor would have a better idea as to what to address conceptually speaking based on the problem-solver's answer choice. In the comments area, please, provide your own assessment examples of how you address specific students' misconceptions.

3) One day one of my children came home ecstatic that he learned the four geographical directions (NESW) through a chant. Unfortunately, the whole chant hinged on knowing where the first direction is supposed to be to proceed with the rest. So, when I asked him about a specific direction, he was at loss for he was not sure what direction he should point for the first direction in the chant. So, it was time for us to go through a brief on the field (both during day light and night time) conceptual encounter with the Astronomy of orienting oneself in space and toss the cute chant in the bin of seeming handy but useless methods of sponging in information.

Share your own anecdotes of such missed opportunities in learning because of "cute" rote teaching approaches. Thank you

No comments:

Post a Comment