Desmos Quickstart Guide

TK Delete most of this

Preparing the Exam for Students to Use a Device

  1. Desmos will tell you the decimal values of intersection points, vertices, roots, etc upon tapping the screen; Consider asking for EXACT values, or asking students to “demonstrate”
  2. (TK) Templates on the blank-graph menu spot?
  3. Plotting piecewise-defined functions is not hard now. (TK) I should consider what other potentional exam questions are no longer hard.
  4. Maybe test mode removes some stuff?

Preparing the Students to Use a Device on an Exam

  1. Show students all the available documentation, and ideally use class time to do a demonstration of the features of the app you’ll be using.

  2. Urge students to use the specified app installed on their own device instead of a TI-83/84+ graphing calculator in class, since that’s what they’ll use on the exams.
  3. Note that the devices don’t have keyboards, only touch interfaces, so when demonstrating how to use the app on the classroom computer try to use only the mouse to simulate screen touches; avoid the keyboard. Desmos offers a pop-up on-screen keyboard in the web app for this purpose.
  4. The online homework (e.g. §3.5) was calibrated on a TI Calc, which for certain non-linear models — Power modes, logarithmic models, and exponential models — will linearize the data before performing regression. This can be emulated in Desmos by enabling ✓ Log Mode. For example, instead doing a least-squares regression \(y_1 ~ ax_1^b\) directly it’ll perform a least-squares linear regression on \(\ln(y_1) ~ \ln(a) + b\ln(x_1)\) and exponentiate to find \(a\) explicitly. This also solves the mystery of why TI-83/84 choose the templates they did for LogReg and PwrReg and ExpReg (and LogisticReg maybe)?

Preparing the Device for Students to Use on an Exam

  1. Before the exam period, lay out all the phones face up on a large surface with space between them, and going row-by-row with assembly line efficiency, (1) power them on, (2) unlock them, (3) start Desmos on each, (4) press the App Switcher (square) on each, (5) pin Desmos on each, (6) press Got it to dismiss the “App is pinned” notification on each, and (7) relock them. Takes 5–10 minutes. This goes quicker if Desmos is still open on the device from when it was last shutdown.
  2. In the classroom, before handing out the exams themselves, proceed to hand out a device to each student, unlocking first it to make sure Desmos is pinned.
  3. Consider casually mentioning they’re cheap Walmart TracFones to dissuade theft.
  4. Announce and write on the board: Hand in your exam and device together, and be sure to collect the devices in this fashion to ensure no student who hands in an exam has not also handed in their device.
  5. Upon being handed the device, there’s no need to clear/close Desmos; just turn it off by pressing and holding the power-button and volume-up-button simultaneously. This way Desmos will remain open but cleared when the phone is restarted.

  6. Protip

    The devices don’t stack well, so they should be laid into a box on their edge, stacked like records in a milk crate. When doing this, be sure to stack them with the power button pointed upward so the device doesn’t accidentally power on.