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IB RESULTS for 2014

July 20, 2014 Leave a comment

Another excellent set of IB results!

  • Higher Level average: 6.67
  • Standard Level average: 6.00

Very well done!

Free programming books

May 26, 2014 Leave a comment

Collections / List object question

April 29, 2014 Leave a comment

Each object in a collection called items has two variables, a String name and an int number. The collection is ordered in ascending order of number.

The collections supports the following methods:

  • isEmpty()
  • getFirst()
  • getNext()
  • getNthObject(int n)
  • hasNext()
  • length()
  • insertAtStart(Obj o)
  • insertAtEnd(Obj o)
  • insertAtN(int n, Obj o)
  1. Write an algorithm using a for loop that prints the names of each object (4 marks)
  2. Write an algorithm using a while loop that prints the names of each object (4 marks)
  3. Write an algorithm that inserts an object o at the correct place in the list (6 marks)
  4. Write an algorithm to sort the collection in descending order (2 marks)

My Answers below. These aren’t the only right answers. There are lots of different ways you can code these.

(a)
for(int i = 0; i < items.length(); i++){
      System.out.println(items.getNthObject(i).name);
 }
(b)
if (!items.isEmpty()) {
      System.out.println(items.getFirst().name);
      while(items.hasNext()){
           System.out.println(items.getNext().name);
      }
 }
(c)
if (items.isEmpty()){
      items.insertAtStart(o);
 }
 else {
      Object tmp = items.getFirst();
      count = 0;
      while (items.hasNext()){
            count++;
           if (o.number > items.getNthObject(count).number){
                 items.insertAt(count, o);
            }    
 }
(d)
 for (int i = 0; i < items.length(); i++) {
      items.insertAtStart(items.getNthObject(i));
 }

Final IB exam times

April 8, 2014 Leave a comment

Standard Level

  • Paper 1 Friday 16th May PM (1h 30)
  • Paper 2 Monday 19th May AM (1h)

Higher Level

  • Paper 1 Friday 16th May PM (2h 10)
  • Paper 2 Monday 19th May AM (1h 20)
  • Paper 3 Monday 19th May PM (1h)

Types of chart you need for the exam and a note on 2-D arrays for SL (??)

April 7, 2014 Leave a comment

I wrote a post on the OCC Computer Science highlighting the discrepancy between the Guide and the specimen paper:

Syllabus point 4.2.4 Teacher’s Note:

“Students will not be expected to construct a flow chart to represent an algorithm in an externally assessed component.”

Specimen SL Paper 1, Question 7:

When the wages for company employees are calculated, all hours above 38 are paid at the overtime rate of 1.5 times the base rate. Construct a flowchart that represents this algorithm.

The reply eventually came back from the IB:

Question 7 in the standard level paper 1 Computer Science specimen paper was included in error as it contradicts the teacher’s note, 4.2.4, in the syllabus.  As per this note, students will not be expected to construct flow charts to represent algorithms in externally assessed components. The IB apologises for the inconsistency in the specimen paper; this will be revised at the earliest opportunity.  It should be noted that students may be asked to draw flow charts when being tested on 1.2.7 in the syllabus.

I also asked about syllabus point 1.2.7.:

Drawing system flowcharts was on the old syllabus, but I notice here there is a reference to DFDs. As I remember from college, a DFD is a very specific thing and drawing one requires quite a lot of expertise. To what extent can students be expected to construct a data flow diagrams in the exam? Does anyone actually teach DFDs in any depth?

The reply came from Dave Mulkey and is worth reading:

Item 1.2.7 specifically says “system flow charts, data flow diagrams, structure chart… UML is not required.”  Lacking specific examples, I am assuming that “system flow chart” has arrows and/or lines connecting modules, “data flow diagram” has arrows connecting modules plus data flow labelled on the arrows, “structure chart” is a top-down hierarchical breakdown of a problem.  The statement “UML is not required” indicates to me that the others are just generic concepts without any specific requirements.  So I don’t think students need to worry greatly about just exactly what is required for a DFD (except that DATA FLOW should be included).  But they SHOULD know that these are NOT algorithmic (programming) flowcharts.  If 1.2 is supposed to be taught in 10 hours altogether, this single assessment statement can’t require more than about an hour to teach, and at most an hour of practice by the students. 

He then points out another problem with the specimen paper and the Guide:

Standard Level Specimen Paper 1 #10 d – asks the students to describe how a two-dimensional array could be used.  However, it is clear to me that only LINEAR arrays are required for SL students, and the 2-D arrays are specifically added for HL students.  So this question is inappropriate for SL students. Be that as it may, I will now teach 2-D arrays to my SL students – briefly – just in case a similar question appears in a real exam.

 

Pass/fail conditions for the IB diploma

April 7, 2014 Leave a comment

The IB diploma will be awarded to a candidate whose total score is 24, 25, 26 or 27 points, provided all the following requirements have been met.
a. Numeric grades have been awarded in all six subjects registered for the IB diploma.Pass
b. All CAS requirements have been met.
c. At least a grade D has been awarded for both TOK and the extended essay.
d. There is no grade 1 in any subject.
e. There is no grade 2 at higher level.
f. There is no more than one grade 2 at standard level.
g. Overall, there are no more than three grades 3 or below.
h. At least 12 points have been gained in higher level subjects (candidates who register for four higher level subjects must gain at least 16 points at higher level).
i. At least 9 points have been gained on standard level subjects (candidates who register for two standard level subjects must gain at least 6 points at standard level).
j. The candidate has not been found guilty of malpractice by the IB Organization.

The IB diploma will be awarded to a candidate whose total score is 28 points or above, provided all the following requirements have been met.
a. Numeric grades have been awarded in all six subjects registered for the IB diploma.
b. All CAS requirements have been met.
c. Grades A (highest) to E (lowest) have been awarded for both TOK and an extended essay, with a grade of at least D in one of them.
d. There is no grade 1 in any subject.
e. There is no more than one grade 2 at higher level.
f. There are no more than three grades 2 at standard level.
g. Overall, there are no more than three grades 3 or below.
h. At least 11 points have been gained on higher level subjects (candidates who register for four higher level subjects must gain at least 14 points at higher level).
i. At least 8 points have been gained on standard level subjects (candidates who register for two standard level subjects must gain at least 5 points at standard level).
j. The candidate has not been found guilty of malpractice by the IB Organization.

Topic 1 notes

March 14, 2014 Leave a comment

Important points:

  • 95% of this topic is common sense. I urge you not to rote learn this — just get a feel for the types of issues that crop up
  • Having said that, make sure you understand 1.2.7. There are two slides dedicated to it.
  • There are three syllabus points that mention social and ethical blah. I have provided an exhaustive list of the type of junk that you have to trot out for these questions in point 1.2.11.
  • If you have any good ideas about 1.2.15 I’d love to hear them

Microsoft_PowerPoint_Icon

Topic 1

 

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