Whatâ€™s so compelling about the three-act math project isnâ€™t that it does a better job of teaching the body of knowledge of mathematics; itâ€™s that it reshapes the cultural practice of mathematics in a way that more closely reflects how grown-ups engage in mathematical inquiry.

That’s the goal anyway, particularly w/r/t mathematical modeling. Pick any definition of modeling you want â€” the IB, the Common Core, the modeling cycle, anything. They all define modeling in similar terms. Here’s the Common Core. It’s scary:

- identifying variables in the situation and selecting those that represent essential features,
- formulating a model by creating and selecting geometric, graphical, tabular, algebraic, or statistical representations that describe relationships between the variables,
- analyzing and performing operations on these relationships to draw conclusions,
- interpreting the results of the mathematics in terms of the original situation,
- validating the conclusions by comparing them with the situation, and then either improving the model or, if it is acceptable,
- reporting on the conclusions and the reasoning behind them.

That is a huge list of important, valuable skills. The scary part is how little our curriculum helps students *develop* those skills. Here’s a task from Pearson’s Algebra I text, which is pretty typical in this regard:

That brave little icon indicating the “Modeling” practice begs the question: *Is* this modeling? Who is *doing* the modeling? Try to locate each of the six parts of modeling in that textbook problem:

- Who is identifying essential variables? Where?
- Who is formulating the model for those variables? Where?
- Etc.

Then do the same for any arbitrary three-act lesson plan.

The three-act structure isn’t the only worthwhile approach to modeling and it’s still a work in progress. But we should all stop pretending that including some real, physical, made-from-atoms item in a word problem does justice *on its own* to the complicated, exhilarating stew of skills we call “modeling.”

**BTW**. While you’re at it, feel free to compare the Common Core modeling *standard* against the Common Core modeling *assessments*. As you may know, there are two consortia developing the assessments. Here is an item from SBAC and an item from PARCC. They are more different than they are alike.

**Featured Comment**

Bowen Kerins offers up a useful analysis of the SBAC and PARCC tasks.