Top 10 Computer Science Tweets for APCS Principles

APCS Principles has a lot of great places to include articles and news about computer science for student readings. Here is a summary of some of the more interesting ones I have posted on Twitter recently:

• Computer chemists win Nobel Prize - great read for #APCSP, and every guidance department in us high schools
• Breaking Brick Stereotypes: LEGO Unveils a Female Scientist
• Data Unit - Ten Simple Rules for Reproducible Computational Research 
• Data  - Future of Statistics  
• Rage Against the Algorithms 
• Potential for #apcsp? Open auto essay scoring engine from CMU looking for pilot schools 
• First 2 3D printers in Haiti - printing umbilical cord clamps & other medical devices. 
• Simple testing can boost CS education 29% overnight!
• Whats the coders responsibility? Facebook-alpha testing program not for the faint of heart
• Advertisers could track your smartphone through accelerometer, researchers find 
• Every Second on the Internet 
• 
  

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String Immutability APCS A Deep Dive

Content has moved to CodeVAs Teachers Lounge - latest post: 

http://www.supercs.net/2015/03/29/immutable-strings/

The String class can cause a lot of confusion for students as they first start working with code. We often introduce it early in the year, indeed it is hard to do many meaningful things without it. The problem is, as an example of a class data type, it can behave in some unusual ways...

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Im the Robin Hood of the APCS Free Response Section

In the AP class we are transitioning from new content towards test prep. While we do AP style problems all year I have just really started talking about strategy for the AP exam itself. On the Free Response questions our theme is Stealing Points.

Grabbing points on the free response --> Heres what I march my kids through:

• Is it a method? Look for return type - does it return an int? 

                         int x = 0;

                         return x;

• while were looking at the return, does it return a boolean? You should probably have one case that returns a true, and one a false. Just a thought
• Does it tell you to return a -1 under certain situations?

                         int x = -1;

                         return x;

• does the problem use an array? Well, we usually use a for loop with those - write one. Use .length
• ArrayList? for-each loop, unless you are removing things
• does the problem ask a question? We use ifs for those. You probably want to access the array/ArrayList there too.

You get the idea - were just looking through our programming toolkit and looking for patterns in the problem.

Now obviously this is a terrible way to solve a problem.  This technique is our worst case scenario. Youve read the problem and have. no. clue. of what to write. It happens to the best kids, especially on a timed test under a lot of pressure.  

Take a second to look over the grading rubrics and think about this technique. We did part 1a in class the other day. In theory you could get over half the points on this question and not have any idea of how to solve it.

Is this teaching to the test? Sure. But what I find is when you remove a kids blind panic and just get them putting some code on paper they often have that light-bulb moment that shows how to solve the problem. And really, writing code on paper is a bit silly, so a game plan is bound to help.

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Marching towards May APCS exam prep

In my APCS class we are functionally done with new topics this year. They are working on searches and sorts the next two weeks, but in my mind that is just an application of the array material we covered back in December.

This is how I pace my AP class...as a spiral. We hit a topic early on, like arrays. Then in the next unit we cover methods, and guess what? Most of the methods I have them write process arrays. We do class design, and here we are back on arrays. My hope is that by seeing them embedded throughout with lots of repetition, they might actually remember a few things about them on the AP exam, or in college, or on Jeopardy. Im a dreamer that way.

To start off we did a day of review about arrays. I gave them some practice exercises, then we did CodingBat  problems. That was Monday. Wednesday we started searches. First I gave them a quiz - I randomly picked one of the CodingBat problems from last class and used it for a 60-80-100 quiz.

 As went over the problem we talked a lot about stealing points on the APCS Free Response questions...did you know you could steal points?

We did the 2009 #1 free response problem. it ties in nicely with a lot of what you see in the CodingBat problems.

Then we did searches. I used Plastic eggs  for the linear search. We did the telephone book trick for the binary search. Heres a video of another way to teach this.

And as a side note, as telephone books become less common I am finding I horde these.

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