Taking Time to Reflect on Learning in MITx

Last week, I decided to return to practice problems in week 1 and complete some of the problems that I did not have time to finish. (Each week I do as many practice problems as I can until working on the homework is all I have time for.) I was happy to see that I could answer these problems (which were about node analysis and voltage divider circuits, two relatively basic concepts) without too much difficulty. I am learning, I thought to myself. I need to spend this time going over what I have learned and making the abilities my own, so to speak. In MITx I am always pushing ahead as diligently as I can and not spending time reflecting on my learning.

The designers have been changing small things in the course. It's interesting to see the changes, such as making the current text in the transcript bold when it is spoken in the video. The word "SPEED" now appears next to the buttons for changing the speed of the videos. Other students make suggestions for changing the interface or adding an interface for mobile users. Not me--I'm usually coming from behind…

Which reminds me: three cheers for Wolfram Alpha! When I needed to compute derivatives for the incremental analysis, I only need to type the equation into the computational engine. (My calculator is not good enough for this.) Students were suggesting a variety of tools--such as a math program you can download from Microsoft.

Still, you know you're in deeper waters when you can't solve the problem on your calculator that was sufficient for any other class you've taken. I'm uneasy that I'm avoiding brushing up my calculus--who am I kidding?--whole new coats of math are needed here! I was able to get a decent grade on the homework, but left the last problem untouched because I could only get through half of the lectures for the topic. I am starting to feel the effects of not having the prereqs. I wonder if MITx will have to enforce a certain prior level of knowledge before letting people take a course. Surely I'm not the only one with these problems...but for the moment this may not be a main concern.

The first exam was announced: it will be in the last week of April, and we have 24 hours to complete it once we begin. I've already marked the calendar and told my wife--who, by the way, did a bunch of my chores to give me time to complete MITx work.

Completing Labs in MITx: Thank Heaven for Trial and Error

Well, I solved Lab 3 with help from my wife and a hint from the discussion forum, and some late night persistence. In this problem we needed to build a series of digital gates that are connected to three voltage sources. Professor says an Intel chip has a billion gates, but our lab involved three, so we start small. Really small.

In Circuits and Electronics, we must complete a weekly lab, an assignment in which we must build a circuit that satisfies certain parameters. Part of the assignment involves getting the appropriate configuration of resistors, wires, and other elements, and another part of the assignment means getting the right values for these elements. It’s a rather safe way to do a lab in basic electrical engineering; I know the only shock I’ll receive is how many times I get the answer wrong.

A lot of my problems with this lab were due to my own ignorance about how to use the circuit sandbox. First, I did not know that you could cross wires in a diagram, which, it turned out, was necessary for the solution to the problem. Of course, crossing wires is acceptable because in an actual circuit, a wire can go over or under a different wire. In my crude diagram, you can see that the red voltage source (the circle) needs to be connected to the red gate (the diamond), so the wire must go over the other gate. I finally found a discussion posting that mentioned that you can cross wires, but another person said that this is in the directions in how to use the sandbox, so I’m to blame for not reading all the directions….One weakness I have is that I am spending more time trying to understand equations than trying to understand the common-sense rules for putting these things together.

But a funny thing is that I was able to get the correct answer by using trial and error to determine the resistance values for these gates. This seems rather unscientific to me, but one hour before the deadline makes me happy for any advantage I may get. And yet, wouldn’t a situation in an actual lab be much much different? For example, at one point, I put the resistance value of a MOSFet so high that I shorted part of the circuit. Now, in the sandbox, who cares, right? But surely this kind of guessing could be dangerous in a real circuit.

One thing I don’t like about the circuit sandbox is that I use “backspace” to delete elements after I’ve selected them. If I hit the button more than once, I go back in the web browser and lose my circuit.