Tag Archives: Java

2014 AP CS A Exam Free Response Solutions

Well, my predictions for the 2014 AP CS A Free Response were close this year as usual.

There was a matrix of classes this year.  It took me 2 years to get this one right.

There were 2 class questions this year and not just one.  I was 1/2 right on that.
You had to extend a Rock which is cool.  I have been having my students extend Actor every year since GridWorld was introduced which is basically the same thing as a Rock.

There was an ArrayList of classes, but the class was a String.  I was kind right on that one.
The ArrayList<String> question was much like a codingbat problem so that was cool.

Circa 2006, there was an interface implementation question this year.  I like the question, but would like it better if the constructor was 3 MenuItems rather than being so specific.  Anyway.

I have posted slides with my solutions and a java student project that has shells and no solutions.  This project will allow students to punch in their code and see if works.
http://www.apluscompsci.com/ap_computer_science_free_response.html

There are review slides for the AP Computer Science A exam for years 2006, 2008, 2010, 2011, 2012, 2013, and 2014.  There are student java projects for 2013 and 2014.

Have a great summer and check out my workshop offerings if you are free this summer.  My workshop is full in Houston with a ton on the waiting list, but my Denver workshop has been expanded and there are still a couple spots left.     http://www.apluscompsci.com/workshops.htm

I also do local workshops for schools and school districts.  If you need specialized local training, email me and we can discuss specifics.

New AP CS A Labs – Magpie, Elevens, and PictureLab

2014 is the last run for GridWorld.  I for one am sorry to see it go.  I have had a fun time working with this case study and have found it to be the best case study of any of the AP CS Case Studies.  There are just so many things you can do with it. Rather than have case studies for the next few years and likely beyond that, there were will be new labs that will serve in the same capacity as case studies have in the past.  These labs will require that student rationalize about existing code and modify existing code.  This will help the students learn what is like to work with code created by someone else and likely work with projects bigger than what they would create on their own. Here are the basics of the 3 new labs.

  • Magpie – string lab where students work with a chatbot program
  • PictureLab – matrix lab that focuses on image manipulation
  • Elevens – card lab that uses lists of classes

Drafts of these new labs can be found at  http://www.cs.rit.edu/~ptt/apcs_labs/

A+ Computer Science Curriculum Materials will provide full support for these new labs.
I have an ap audit-approved syllabus posted that incorporates the new AP CS A Labs.

These labs will also be used at my AP Summer Institutes in the summer of 2014.

New Contest Prep Materials Info Posted

Information on all A+ Computer Science Contest Preparation Materials has been recently updated.  You can get information on new materials by visiting the A+ Contest Materials page.  Java 7 topics will be a bigger focus this year.

2013-2014 UIL Computer Science Topic List

The official UIL Computer Science written test and packet writer will be writing tests and packets again this year for A+ Computer Science.  The tests and packets will reflect the current test and packet style used by UIL Computer Science.  The content will also be similar, including the 5 open ended non-language specific questions at the end of each test.

I will be updating my contest dates page soon so send me an email if you dates already set in stone. The Houston area will kick off the programming contest season in early October.  7 Lakes will be starting it off once again this year.

2014 Houston Area Contest Dates
Oct 11 – Seven Lakes Kickoff Classic
Oct 16 – Dulles HS Contest
Nov 8 – Taylor Halloween Contest
Nov 15 – Clements Thanksgiving Contest
Dec 6 – Tompkins UIL Fall Meet
Dec 13 – Cy Woods Christmas Contest

AP CS A Exam 2013 Wrap-Up

Well,  Another AP Comp Sci Exam has come and gone and I can say that I am kinda sad, but not really.  My crew felt that exam was very familiar, but a bit more tricky than in years past.  I guess I agree with that considering I went over every single thing on the exam 50 plus times.

I have posted my solutions to the 2013 FR questions and a Java start-up project on my A+ site.

Each year I like to post some of the best make-me-laugh / make-me-writhe-in-pain comments heard 48 hours after the exam.  Here is my top 4 list for 2013.  Some of these really did make me cry and not from joy.

Numero Uno – “I know you said that we absolutely had to call part A on part B if it said to do that, but I just went ahead and rewrote my code from part A on part B – I think it mostly worked.”
[ Arggggggggghhhhhh! ]
Numero Dos – “The Grid is a matrix?   When did they change it to that? ”
[ Sneaky, they are. – say this in your best Yoda voice as it is way funnier that way. ]
Numero Tres – “There was a Song problem on the exam just like the one we did in class, but you made us process 10,000 songs and the exam example only used 20 songs.  I was so confused.”
[ I deleted all of the songs from my iPod except for 20. I am now a changed man. ]
Numero Quatro – “You said there would be a matrix of classes on the exam.  You were totally wrong as the test had a matrix of doubles.”
[ Yep, doubles are way more complicated.  Boustrophedon!  ]

I posted my predictions last week and I think I was spot on for the most part.  You can check out the post below.  I did predict a matrix of classes so technically, I was off by one on that one – OBOB.

Have a great summer!
All of those going to grading, have a great time and rock the grading!

Good Luck to all on the AP CS A Exam

Good luck to all on the upcoming AP CS A Exam!

As I have taught the course for nearly twenty years and spent many years studying exam trends as a grading reader, a grading leader, and consultant, I am aware of the main topics to cover, but I really focused heavily on four main areas with my students in prep for this year’s Free Response section.

1.  ArrayList of Classes / References –  there is always a question that requires students to work with an ArrayList<NeverSeenThisClassBefore> that involves lots of drilling down to get to the various pieces.  You must be comfortable with abstraction to handle this type of question.  Working with GridWorld helps!  Working with lists of integers and doubles will not be enough.  Go all of the way back to 2006 and you can see where this whole question thread started.

2.  Make a Class from scratch – you may have to implement an interface or extend an abstract class, but probably not.  That type of question went away about 5 years ago.  More than likely, the students will have to extend Bug or Critter to make a new class that will involve method overriding and such.  Pretty simple, but requires some practice.  You could get an APLine question, but most likely, it will be a GridWorld question.

3.  Processing an Array – this could be an array of classes like last years Horse[] question, but who knows.  2012 was the first year the AP exam had an array of classes / references.  Most of the time the array question just involves some algorithmic stuff with numbers like finding smallest, largest, difference between smallest and largest, etc.

4.  Matrices – matrices are back and boy am I glad.  I love the matrix – what a great movie!  Last year was the hardest matrix question in the world – you had to count 255s!  This year will probably be more like the route cipher from 2011.  I have prepped my students on Matrix[SomeClassFromMars][SomeClassFromMars] as I assume that a matrix of classes would throw a serious curve ball at most students.  I also did some work with transposition ciphers as I really like ciphers.

I will post comments after I see the actual Free Response questions next week and let you know if I was close or not even in the ballpark.  I have been very accurate with my predictions in the past.

If you want to see slides I have used as AP Exam review slides in the past, I have some of those posted that you can download.

If you like my humor and want to spend a week hearing more about how I prep students to rock this exam, check out my workshops over the summer.

Finish Strong and Rock the AP Exam!

UTD High School Programming Contest

The UTD High School Programming Contest is this Saturday the 13th.
Good luck to all competing.
The basic schedule is listed below.
There is still time to register if you are interested.
Contact Dr. Ivor Page if you want in on the fun.

10:40a Practice contest begins
11:30a Pizza and soft drinks for lunch (sponsored by Award Solutions)
12:00p Main Contest Begins

AP Summer Institutes Underway

My AP Summer Institutes are under way.
The June 6-9 workshop in Houston, Texas was a blast.
We covered tons of material, including Scratch, Jeroo, Alice, GridWorld, and lots of Java.
The food and conversations were great!
It was fun to meet people from all over and make some new friends.

My next AP SI in in Kentucky running from June 27 – July 1.
See all of my workshop dates.
Follow my travels across the US to my workshops via my son’s travel blog.

2011 CS Contest Season Ends

What are Computer Science Contests?

Computer Science contests are huge in Texas.  Basically, you have a contest every two weeks if you live in Houston or the surrounding area.  In the fall, the contest season starts in early October with the 7 Lakes Kick-off Classic which starts the whole contest circuit.  The season wraps up each year in May with the UIL State Academic Meet Computer Science Contest.  This state contest is the culmination of all of the local contests.

Each contest typically has a programming component and a written test component.  The programming component consists of a packet of problems that each team must attempt to solve.  A standard packet will have 12 problems.  A more expanded packet may have 18.  Each local contest has the option to create their own packet and set the number of problems.  The UIL Computer Science Contest, a statewide contest in Texas, has 12 problems so that is the number most local contests go with.  The written component consists of a 40 question multiple-choice test.  Test questions focus on logic, algorithms, data-structures, and language features.  All tests used in Texas use Java as the testing language.

Why take teams to contests?

Contests force students into a real team environment with the added pressure of finite time.  Most programming contests only last two hours and only allow teams to use one computer.  Teams must learn how to share a single computer and work together in a timed environment to solve problems.  Students learn valuable teamwork and problem-solving skills in these settings each and every time they compete.

Another benefit is that many large software companies use similar problems for interviewing purposes as those often seen in contest packets.  A common programming problem often involves determining if an exit from a maze exists.   A former student of mine was asked to explain solving this exact problem when interviewing for a Google position.

Winning is contagious!  Get a few students to go compete and actually win and your enrollment will spike upwards.  All students want to be a part of a winner.

How do I get involved?

If you are in Texas, check my contest dates page.  Several Texas contests are already posted.  If you are in another state, find out who hosts contests or host your own.   Check out my site for information on hosting your own contest.

Looking forward to next year

The contest season here in Texas just wrapped up.  It was a ton of fun and I look forward to what next year holds.  Good luck!