Tag: teaching with technology

Two apps I use everyday as a math professor

For a long time I was a smartphone skeptic – happy with my dumbphone all the way up to 2010 and of course very judgmental of anyone I deemed to be “wasting time” with such a silly device. Well, here we are in 2015 and I have had my smartphone for more than a year and just like everyone said, it has become an indispensable tool.

Naturally I have a lot of cool apps right? (like neko atsume!) Sure – but there are a couple that actually help me day to day with my job.

#1 Wabbitemu

Wabbitemu will turn your phone into a TI83, TI84, or even the fancy pants TI84+. Writing an exam key and too lazy to go find your graphing calculator? Well this has you covered. I went old school and set it up as an 83. This is a screenshot straight off my phone (it sets it up so the phone menus only come up when you click).

wabbit emu screenshot android



#2 Camscanner

Our online students take all of their exams on campus at our testing center. In the past, when I graded exams, the online students wouldn’t have the same experience of seeing all the feedback since they wouldn’t necessarily see the whole exam unless they picked it up. Camscanner has changed all of this. With a few clicks, you can create a really nice PDF using any picture or pictures (each picture can be set to be its own page).

2015-09-15 22.05.53


So take a document, snap a pic of each page, and boom – nice PDF handout.

The screenshot above is from a time where I wrote the entire key to a practice exam on the board but hadn’t yet typed it up. Realizing that about 50% of my students were just taking pictures of the key instead of writing it down, I decided to test if the app would make a good PDF from something like this and it did. Really impressive (and now I don’t have to type up the key).

Honorable Mention: Panecal Plus

I can’t explain it, but when I want to just do a quick calculation, I tend to want to use a simpler calculator. That said, the default calculator on android is just TOO simple. Here is where Panecal Plus comes in. This is an awesome little scientific calculator.

panecal plus screenshot andoid


There is a free version supported by ads, but I like to pay for an app when it’s good so that I can help support developers more directly.

The “I don’t know why I have this but it is still cool” app: R Console Premium

One other honorable mention goes to R Console for Android. You ever just want to code a quick simulation but you aren’t near a computer and don’t care if you can save your code. Yeaaah. Maybe I haven’t either but it doesn’t mean this app isn’t cool.

R Console android


I swear that I really have used this a few times! How often was it NOT because it just looks cool? Well, I don’t know the answer to that lol.


And here you thought this post was going to talk about wolfram alpha right?




Generate a data set with a given correlation coefficient

Recently, I found myself needing to create scatterplots that represented specific values for the correlation coefficient r. This was for a writing project, but it is something that has come up with teaching as well. Showing students scatterplots for many different values of r seems to really help them conceptually, especially when it comes to understanding that not every data set with the same correlation will look exactly the same. Unfortunately,  I have always been at the mercy of what examples I can find online or in textbooks. With this in mind, I set out to figure this problem out once and for all.

The problem: Given a desired correlation coefficient, generate a data set.

As it turns out, this is not that difficult of a problem! Using this overall solution, I wrote a simple function in R.

make_data_corr = function(corr, n){
x = rnorm(n,0,1)
y = rnorm(n,0,1)
a = corr/(1-corr^2)^0.5
the_data = data.frame(x,z)

The inputs here are corr (the desired value for the correlation coefficient) and n (the desired number of paired data values). You will notice that I didn’t add any kind of validation or anything like that to this function, so if you put in a strange value for r or n, you are on your own. The resulting output is a data frame with your data set being x and z. Here is an example of it in action:


scatterplot-RAt smaller sample sizes, the correlation coefficient is CLOSE but not exact. Here, r = 0.92 but when I ran the function again with n = 350 I ended up with r = 0.83. For my purposes this is good enough, but it is a consideration for possible improvements (at this stage, I haven’t thought about how to approach this).

Eventually I may make this into a small webapp that anyone can use (including myself). Until then, if you find a use for this or find a way to make this better, certainly let me know. It is an interesting little problem to play with!

Math screencasting – tools I use

It’s been several years now that I have been adding articles and videos to Mathbootcamps and there has been quite a learning curve as far as best practices and tools of the trade. After starting to teach online courses, it became even more important to have a “system” and I can finally say that I am happy with my full setup! In this post, I will talk about the tools that I am currently using the produce my screencasts.


Camstudio – this is my screencasting software of choice. This is 100% free and works as well as the $600 solutions I have seen elsewhere. The only real trouble can come from making very long videos. If your video is over 2 gigs (hard to do, but possible), this will simply not save the file. But, a good practice is to keep your videos short (not something I am always good at!) so this is a nonissue to me.

Zoomit64 – this is a free tool from microsoft that allows you to write on the screen of any windows computer. Prince George’s Community College has a really nice cheat sheet for working with it including shortcut keys (you want to know these!).

Powerpoint (or other presentation software) – Of course, there are plenty of other tools out there for making presentations. This is more of a familiarity thing for me as I can work with it quickly. In this case you could really use any tool. You just need a way to show some of the math that you are talking about onto the screen for recording etc.

TI-Smartview – this lets me show the calculator and buttons full screen (example). Another option would be to simply film the calculator but this looks much nicer in the end product. You just have to be careful – the 2 gig limit with camstudio will come up quickly here (I would say more than ~5 mins with the calculator at full screen is too long).


Headset – while there are many fancier ones out there, I am currently using this 10 year old+ cyber acoustics headset. Personally, I find that I like having one ear open so I can hear myself better when recording.



In other words, you don’t have to go really crazy with the quality here. For our applications, you simply need something that will pick your voice up clearly. The adjustable mic is very important though because you want to maneuver this to avoid air bursts (pops when you say something that starts with “p” for instance) and so that we don’t hear your breathing in between every word!

Writing Pad – this is probably the biggest investment you will have to make. I have used the “cheap” $80 version for years and had no trouble. I did purchase the more expensive bamboo tablet and found that it was somewhat less responsive (perhaps it is better for art?). These are also nice to have laying around if you do a lot of math writing in word since mathtype now works decently with the math input panel.

That’s really it! Not a huge setup and it has allowed me to make a TON of videos at this point. You can see examples of what Ive made with this setup here: https://www.youtube.com/user/MathBootcamps/videos.