Thursday, July 22, 2010

Goodbye Plug and Chug, Hello Substitute and Evaluate

Mathematics is a very challenging discipline for many people. So, why do textbooks and teachers make it even more confusing by communicating poorly? Our students are capable of understanding the concepts if we would use the proper terminology. For example, why do we tell students to plug and chug? What does it really mean to plug and chug? What we really want the students to do is substitute the value into the expression and evaluate. I know what you are thinking, what is the big deal? After all, students knew that when you told them to plug and chug you meant place the value in for the variable and perform the order of operations. Well, have you thought about what happens when on a standardized test the directions say to substitute and evaluate? Have you noticed that students try to solve algebraic expressions? Why? They do not understand the difference between an expression and an equation. Here is another example. How many books and teachers ask students to reduce a fraction? Doesn't reduce mean to make smaller? Does the fraction actually get smaller? No, the fraction is equivalent! No wonder students have difficulty understanding the concept of a fraction. What we should be asking the students to do is simplify to lowest terms. One last example, how would you read -3? If you said minus three, doesn't minus mean subtraction? Isn't this really negative three or the opposite of three?

Don't feel bad if you are guilty of poorly communicating the mathematics to your students. In many instances we are mimicking what was in the textbook and relying on how we were taught mathematics. I would encourage all math teachers at all levels to think about the terminology they use. If you are in the habit of using mathematical slang or poor terminology, try to break the habit as soon as possible. Discuss this issue with other math teachers at your school. If everyone begins to use proper terminology, students will also use proper terminology and you will see them make great strides in being able to communicate mathematically.


  1. Jeannie~
    I never thought about all the incorrect vocabulary concepts we are teaching children in Math until reading this post. Although I have never heard of plug and chug before, I do see how the use of that could confuse students on a standardized test when it says "substitute and evaluate." Without having the opportunity to clarify directions with them, I am sure many of them would be off in left field. I am curious if you have ever had discussions with your students about the differences in terminology that they have heard in their math careers? Maybe by communicating this with the students, they will keep us on our toes and break a bad habit.

  2. Kacey,
    I constantly speak with my students about communicating their mathematical ideas properly and the importance of using correct vocabulary and terminology. Needless to say they love it when they catch me using any mathematical "slang"! Once we (the department) started to focus on the math vocabulary, our students did help keep us on our toes by pointing out to us times when we slipped back into our bad habits. Some of my college bound students reported back to me that their college professor used "plug and chug" and that it actually bothered them to hear this!

  3. actually, my students all kinda liked the plug and chug referral - -and we were all reminded of the glade commercials. --- plug it in, plug it in!
    many remembered what to do because of this.
    Having said that, this should only be a small piece of the curriculum, anyway, unless of course you are teaching them to be really good problem solvers, so that this is really only the last step of the proces.. (the plug part, not the chug.)

  4. I don't understand the last comment. Isn't the point of all disciplines to produce good problem solvers? Maybe I am misreading.