Category Archives: #industry

Real World Math: Project Manager

When I first started this blog the idea was to categorize assignments based on a series of twitter style hashtags, which would ultimately allow a teacher to quantify how differentiated their lessons had been – in a macro sense at least.  I have not really stuck to that idea, but one of the original hashtags I had was #industry.  The purpose of #industry was pretty simple – someone had to do this in their job.

I was hoping that #industry would end up as a collection of problems that come directly from people’s  work experiences.  These experiences would be served to student’s unedited from the workplace to the classroom.  Inherent in this hashtag would be the answer to the question “why?” because presumably anybody doing something for their job would have a clear reason as to why they were doing it. (presumably?)

So here’s the problem:  My fiance is a project manager and she had one site that was 3/4 an acre and a price from that site for $54,000 for some work. Then she had another site that was 2.5 acres and needed to know how much that same work would be for the larger site.  That was the first thing she needed to calculate, but she ended up just wanting to know how much 1 acre was worth, so she could scale it to all her other jobs.

Here’s an error analysis angle to this question –  To scale the cost for 1 acre she had initially multiplied 54,000 by 1.25 and she was genuinely curious about why that did not work.  Hhhhmmmmm…


Cable Design for Satellites

The Description

This is an activity that was created by a harness and cable engineer in the aerospace industry. He is in charge of designing all interconnects between all the various systems / components on a satellite. This is an actual design problem that he made during the course of his job. The only thing he changed was the length of the wire from the ICB300 to the LAE ,because he wanted the 24AWG wire to result in a voltage drop greater than one, in order to test whether the students would see that and move to a larger wire.

The solutions are on the second page of the pdf. These solutions were authored by the engineer who wrote the problem.

I have a simplified version of this problem in my Satellite Design Teams activity.

The Advice

I would make sure that the students know this is an actual design problem for a satellite.  It is not a simplified representation of a problem someone might do, rather it is a real problem that someone must do, in order for the satellite to achieve mission success.

Looking at the equation again:  V = L * R * A.  V is the voltage drop, which is what they are solving for.  L is the lenght of the wire, which is given in the problem.  R is resistance, which they get from the table (they first choose a wire size, then look at the table for its resistance).  A is amps, which is given to be 0.8 in the first bullet point of the problem.

So basically, A is constant, and the students are inputing some value of L and R, in order to find V.  Then they are adding up all their V’s, and seeing if the sum is less than 1.

The design tradeoff between weight / voltage drop is key here.  Large wires have very low voltage drop, and since we cannot have a voltage drop greater than 1V, we are tempted to just use very large wires.  But large wires are also heavy, and satellites need to be as light as possible.  Thus the tradeoff between weight and voltage drop.  We must select the smallest possible wire, that still has a voltage drop less than 1V.

The Goods

Wire harness exercise


These are a listing of hastags that I use to catagorize my lessons plans.  Each catagory represents a different style lesson plan.  My instructional goal is typically to make sure that I use each hashtag at least once a month.  The goal of this blog is to share all the lesson plans that I use under each hashtag.

My detailed lesson plans are my Keynote slides.  But along with those, I make a quick, calendar-style overview to me a general idea of what I am doing.  It’s on this calender where I place the hashtags at the bottom of each day.  This allows me  to quickly look back at what I have been doing, and know whether of not I am differentiating.  For example, here is two weeks worth of my lesson plans in geometry.  Notice that I can quickly see whether or not I have differentiated my instruction, without having to analyze each specific lesson plan.  The hashtags allow me to get a quick sense of what I have been doing, and what I have not been doing.


*Notes –

-The term “perplexity” is being used as described by Dan Meyer here