## 22 September 2019

### Host your own version of Desmos for testing purposes

Even though it is a math app, as a physics teacher, I love Desmos!   I encourage my students to use it as their primary calculation tool.  If you are new-ish to Desmos, you might want to read a previous post about using Desmos in the physics classroom (here).

One feature I like is that Desmos can solve linear and quadratic equations, even in non-standard form.  Below is the solution to the question "A ball is thrown up at 25 m/s from the edge of a 30 m cliff.  When is it 15 m above the base of the cliff?".

Before Desmos, I would see many students set up the correct equations from the equations of motion, but then foul up when transforming that equation into standard form, therefore getting erroneous answers.  Desmos removes that chance of screwing up.

However, the above feature is not available in the Desmos Test mode.  While there is a work-around (see the post-script below), it adds extra steps and and extra chances for student mistakes.  Allowing students to use the full-featured Desmos on tests and quizzes is problematic.  If students create a Desmos account, they can save past work, which could then be used as a "cheat-sheet".

Here is a way to allow students to use the full Desmos but in a secure way.  To do so, you need to be able to lock your students' electronic devices to a single website.  Since my school is an ipad school and we use Apple Classroom, doing so is easy for me.  You just need to create a website using Desmos' API.

To create a revenue stream, the Desmos team wants commercial companies to embed the Desmos product into their website.  As such, Desmos has developed an API (application program interface).  As of this time, Desmos allows non-commercial sites to use the API for free.  You can check out what they offer at desmos.com/api .

To create my site, I used Google Sites and created a basic site.  I then went to the Desmos API site and opened up the "default state" example.  I then opened up the source code (exact steps dependent on OS and browser), copied that code, and then pasted it into my website.  I did do some modifications to make degree mode standard, but that was optional.  And now my students have access to all the computational functions of Desmos, and I have the knowledge that they cannot create cheat-sheets.  You can view this site at http://bit.ly/2m3C9Ei

Post-scripts
If you must use Desmos Test mode with your students, you will have to get them to transform their equation to standard form (...=0) and then replace 0 with y.  Unfortunately, those 2 steps can flummox many students which is why I did the above.  See the example below.

If you do decide to host your own version of Desmos, you should ask permission just to keep things legal.  There should not be a problem.  Here is what Desmos sent me when I asked such.

Hi Michael,

We're happy to have you integrating the Desmos API! So long as this is for non-commercial purposes, please go ahead and use this API Key that is listed in the Desmos API 0.6 documentation: xxxxxxxxxxxxxxxxxx. I would also encourage you to check out Learn Desmos to learn more about the functionality.

If you would like to embed screenshots as well, just follow these guidelines:
• Screenshot in offline content should include Desmos logo
• Screenshot in online content should include Desmos logo plus a Desmos hyperlink
• A video without audio should include Desmos logo, plus Desmos hyperlink if online (e.g., YouTube)
• A video with audio should has same as above plus the speaker mentioning the graph is "powered by Desmos" (see Mathalicious example, Q3 -- bottom right)
• Branding and icons

If this is in fact for a business, just let me know and we can make a plan!

Best,

Kristin