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Edit: This activity has been completed. See STEM Behind Hollywood: Zombie Apocalypse Part 2 (TI-84+CSE) to download the finished activity.

I've been gradually working my way through the five existing STEM Behind Hollywood activities for the TI-Nspire from TI Education, porting them to the trusty TI-84 Plus C Silver Edition platform. I started with Earth Impact!, which was tested by TI Education president Peter Balyta himself, then created Zombie Apocalypse Part I. The obvious follow-up is Zombie Apocalypse Part II, an even more in-depth activity that teaches students pH, anatomy, more immunology and epidemiology, and is quite fun to boot. Unfortunately for me, it's an extremely in-depth activity, with 33 pages of text, two types of simulations, and three image pages.

So far, I have transcribed and delineated all 33 pages of text, although they still need to be proofread. One of the simulation is exactly the Game of Life-like simulation from the first Zombie Apocalypse activity with a few labels changed and red turned to turquoise, so re-using my assembly program from Part I was easy. The second simulation, in which students perform a titration, is quite complicated and remains the largest single part of this program that I have not yet completed. In addition, I will of course have to re-write the Student Guide and Teacher Notes documents that are distributed along with this activity.

I'm excited to bring this activity to teachers and students who use the TI-84 Plus C Silver Edition calculators in their classroom, and as always, I'll be keeping this topic updated while I develop this new activity.

Looks like you are off onto a solid start with this one. Smile Not sure there is anything I can offer to help this along, other than continued support and proof reading, as it is needed. Good luck Smile
Thanks, I appreciate the moral support, which is pretty much exactly what I need for now. Smile One of the biggest challenges remaining to me is figuring out how to map the two remaining available F keys (ZOOM and TRACE) to the many controls titration requires: the stir plate, the dropper, and for the second simulation, a microscope. Thanks in advance for the proofreading offer.
*bump* One of the things I need to figure out for the titration simulations is what the equation for the pH curve is. Unfortunately, reviewing online resources revealed that there's no clean equation to describe the equation for titration of a strong acid with a strong base. Happily, I was able to use the points from TI's simulation to model the curve myself, based around a modified logistic curve. The function I came up with is:

Code:
pH = f(base_vol) = y_off + L/(1 + e^(-x_mult * (base_vol - x_off))) + linear_fac * (base_vol - linear_off)
where:
- base_vol = independent variable = volume of base added
- y_off = constant Y offset
- L = constant logistic coefficient
- x_mult = constant base volume coefficient
- x_off = constant base volume offset
- linear_fac = constant coefficient of linear term
- linear_off = constant offset of linear term




Edit: It turned out that reverse-engineering the equation for the pH for the second titration was much easier. I was able to fit a polynomial to the points on the TI-Nspire:
pH = f(base_vol) = -0.0002 * base_vol ^ 2 + 0.0161 base_vol + 7.4115
(With R^2 fit = 0.9999)
Impressive work! This is why you get paid the big bucks, right? Very Happy I am not sure I'd have been able to work the equation like that on my own.
tifreak8x wrote:
Impressive work! This is why you get paid the big bucks, right? Very Happy I am not sure I'd have been able to work the equation like that on my own.
I'm sure you would have figured it out. Smile I started from knowing that the graph resembled a logistic function, just offset in X and Y and scaled in both directions. I also noticed that there must be a linear term, since the original graph slopes slightly up throughout its length. Therefore, my solution was to create a function that was a sum of an offset, scaled logistic function (L/(1+ke^-x)) and a linear term, and adjust the coefficients and offsets until everything lined up.
*bump* I have long been dragging my feet on this project, but I am aware that the year is waning and I still have three more of these to release. Here's my progress in about half an hour this evening drawing the pipette, beaker, and pH sensor for the titration simulation. I still need to color in the stir plate's front face, adjust the sprites to match, make a pipette holder sprite, and display it along with a support piece.

That calculator though.

Daggum that looks awesome. Is this supposed to symbolize sensor data being retrieved by the calculator? I confess I've not looked into the Nspire version, so I don't know.
KermMartian wrote:
*bump* One of the things I need to figure out for the titration simulations is what the equation for the pH curve is.


Couldn't you have just looked at the lua code in the Nspire document?
Looking very nice Kerm! The graphics are very well done. Smile
tifreak8x wrote:
Daggum that looks awesome. Is this supposed to symbolize sensor data being retrieved by the calculator? I confess I've not looked into the Nspire version, so I don't know.
Thanks! Yes, it is the calculator reading the pH of the solution in the beaker. A pH graph will be drawn in the upper-right quadrant of this simulation.

Ivoah wrote:
Couldn't you have just looked at the lua code in the Nspire document?
I don't have any method of viewing the source of .tns files.

MateoConLechuga wrote:
Looking very nice Kerm! The graphics are very well done. Smile
I appreciate it!

Here's my current progress from working on a bus this morning:
KermMartian wrote:
I don't have any method of viewing the source of .tns files.


If you open the .tns file with the Nspire student software you can click on Insert > Script Editor > Edit script to edit the script on the current page
Ivoah wrote:
KermMartian wrote:
I don't have any method of viewing the source of .tns files.


If you open the .tns file with the Nspire student software you can click on Insert > Script Editor > Edit script to edit the script on the current page
I believed that the Student Software required money; am I wrong about that? If I am, I will certainly do that. Does that mean there's no way to edit-lock Lua programs?

Also, if anyone has the Zombie Apocalypse Part II program handy on their TI-Nspire, I realized that my notes about the titration simulation are a bit incomplete. Specifically, I recorded molecule counts in the little beaker on the right side of the simulation up to the vertical pH asymptote, but I only took a screenshot of the final state, where pH ~= 12.70. If someone could take a screenshot or two when the pH is between 1.0 and about 3.0, and also make a note of whether the following lines are roughly correct, I'd be hugely grateful. The titration simulation is about eight pages into the activity; you can't miss it. Smile

Code:
0 mL   1-1.01   9 H+, 9 Cl-
3 mL   1.08   8 H+, 9 Cl-, 1 Na+, 1 H2O (blue)
6 mL   1.17   7 H+, 9 Cl-, 2 Na+, 2 H2O
10mL   1.31   5 H+, 9 Cl-, 3 Na+, 4 H2O
Looks to me like it does cost money, but there is a 30 day free trial as well. Smile

Good luck Kerm! (If only I owned an Nspire..) Smile

Link: http://education.ti.com/en/us/software/details/en/4DCD444963B04332A10DCF8CC455EF43/ti-nspire_pc_trial
So, At 1 pH, I see 9 of each red and yellow.
At 1.5 pH (takes a while to get it there) I have 9 yellow, 6 blue, 3 red, and 4 grey.
At 2, 8 grey, 9 yellow, 8 blue, and 1 red

It jumped to 7 pH at that point. Couple screenshots:

Great, that confirms my notes. Unfortunately, I got lazy around that asymptote, so I missed the fact that at pH = 7, there are 9 each of H2O (blue), Cl- (yellow) , and Na+ (grey). However, if you use up all 50mL of the additive, all the H2O seems to have turned into Na+. Is this actually a thing that happens, or is my screenshot at pH=12.70 wrong?
KermMartian wrote:
Ivoah wrote:
KermMartian wrote:
I don't have any method of viewing the source of .tns files.


If you open the .tns file with the Nspire student software you can click on Insert > Script Editor > Edit script to edit the script on the current page
I believed that the Student Software required money; am I wrong about that? If I am, I will certainly do that. Does that mean there's no way to edit-lock Lua programs?


How did you get your Nspire? A student software license key came with mine.
Ivoah wrote:
How did you get your Nspire? A student software license key came with mine.
It was signed by Mayim Bialik (TI's spokesperson) and given to me as a gift by a friend.

Anyway, I haven't had much time to work on this, but I finally bit the bullet and wrote the code to make the titration simulation work. The pH isn't shown yet, and the beaker containing molecules is AWOL, but it functions properly. I haven't tested the second titration yet, but I've put in the code to hopefully make it work equally well. I've also worked on the graphs that the simulations generate. The graph at right below is the graph page corresponding to the first titration.

That is some nice animation there! I do like how it shows the graph as the simulation runs; that is really neat. Smile Is this the thing with the molecules in the beaker, or is that something else? Razz
  
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