rate of change


  • Slope, Constant of Proportionality, Unit Rate, Rate, Rate of Change

    Slope, Constant of Proportionality, Unit Rate, Rate, Rate of Change

    A question was posed recently that I find intriguing and important. The question was, “what is the difference between slope, constant of proportionality, unit rate, and rate of change?” I researched the answer to this to evaluate my own understanding of these terms. Here is what I found (and am open to feedback as my…


  • Slippery Slope – 3rd Grade Multiplication Word Problems to Slope in Algebra

    Slippery Slope – 3rd Grade Multiplication Word Problems to Slope in Algebra

    Top left is a scaffolding I use to help students learn to solve math problems using multiplication (3rd grade). The situations are typically rate problems (e.g., 5 pumpkins per plant or $2 per slice of pizza) although the term “rate” is not used yet. The same concept of rate plays out in high school with…


  • Rate of Change in Real Life

    Rate of Change in Real Life

    61 cents per ounce is a rate of change. Graph the line modeled by this (y intercept is 0) and it becomes slope of the line. In referring to algebra we often hear, “when will I ever need this?” My response is “all the time!” Our job as teachers is to make this connection for…


  • Introduction to Slope

    Introduction to Slope

    Slope is one of the the most important topics in algebra and is often understood by students at a superficial level. I suggest introducing slope first by drawing upon prior knowledge and making the concept relevant (see photo above).  This includes presenting the topic using multiple representations: the original real life situation, rates (see photo…


  • Interpreting Slope Intercept

    Slope is one of the most important topics covered in high school algebra yet it is one of the least understood concepts. I have two observations about this. First, slope is often introduced with the formula and not as a rate of change. Second, students intuitively understand slope as rate of change conceptually when presented…


  • Intro to Slope as Rate of Change

    Slope may be the most challenging concept to teach in algebra yet it is one of the most important concepts. I use the following sequence to introduce slope: rate of change, rise over run, rise over run as a rate of change. The first photo is a map of Manhattan with directions on counting city…