AP Computer Science Principles Exam: Tips for Test Day
Whether you want to major in computer science or learn coding (or both), you probably know the AP Computer Science Principles A course.
It’s an introduction to Java and programming as a whole. The course comes with an AP exam, which probably sounds intimidating.
But don’t worry – this guide to the AP Computer Science Principles Exam will help you tackle the exam and hopefully even score a 5.
The AP Computer Science Principles exam consists of two sections.
The first section is 1 hour and 30 minutes long and contains 40 multiple choice questions. These questions can be from any unit (1-10). The second section is also 1 hour and 30 minutes long and contains 4 free response questions.
Here are the skills and topics covered on each section, respectively:
Methods and Control Structures – write individual methods
Classes – write a complete class that satisfies the requirements
Array/ArrayList – create, traverse, and manipulate 1D arrays or ArrayLists
2D Array – create, traverse, and manipulate 2D arrays
Important note: if you’re taking the exam in 2022, the College Board hasn’t confirmed whether the test will be written or typed. It’s wise to prepare for both the pen/pencil version of the exam and the computer version.
Key Concepts Covered on the AP Computer Science Principles Exam
The exam is based on the Java programming language. The content is cumulative, meaning that you need to understand previous topics in order to understand the current topic and so forth.
Here’s a breakdown of each unit and the most important info that’s taught. The percentages are estimates on how much of the multiple-choice questions cover the specific topic.
Unit 1 – Primitive Types (2.5-5%)
When int and double are added, subtracted, multiplied, divided, or %ed (modulo), the result is a double
When two ints are divided, the result is an int – simply erase the decimal and numbers that go after it
8/3=2
Unit 2 – Using Objects (5-7.5%)
Understanding the basic structure and syntax in Java
Unit 3 – Boolean Expressions and If Statements (15-17.5%)
Demorgan’s Laws
Unit 4 – Iteration (17.5-22.5%)
Mostly loops
Unit 5 – Writing Classes (5-7.5%)
A class is like a framework for an object; objects are an “instance” of a class
Don’t forget constructors when writing a class!
Public vs private
Unit 6 – Array (10-15%)
Difference between the normal for loop and the for-each loop for arrays
For loops use [i] or some form of it, so use this when you’re changing something in the array.
For-each loops create a copy of stuff inside the array, so you can’t change the array.
Unit 7 – ArrayList (2.5-7.5%)
Similarities and differences between array and ArrayList (I won’t explain here because it’s a huge topic but feel free to look it up)
When you remove an element from an ArrayList, the elements that go after it shifts like when you successfully remove a whole row in Jenga.
Unit 8 – 2D Array (7.5-10%)
An array of arrays
Draw a table with rows on the left and columns on the right
Unit 9 – Inheritance (5-10%)
Public variables and methods get inherited
Private or static variables and methods don’t get inherited
Pay special attention in class for this topic and go to office hours whether you have a question or not. Trust me here.
Unit 10 – Recursion (5-7.5%)
Always find the base case and use that to trace the recursive statement
You’re not asked to write recursive methods on the free response section
Study Tips for the AP Computer Science Principles Exam
Practice. To score a 5, you must be familiar with the type of questions the AP Computer Science Principles exam will throw at you. The more you practice the less time you’ll waste on each question because as you practice, you’re learning test-taking strategies specific to this exam.
Don’t cram. Study at least two months ahead of time and be consistent with how much you practice every day. Review every unit and make sure you understand all the concepts of one unit before moving on to another. For example, if you don’t feel confident in doing array questions, spend more time reviewing them. After you finish reviewing all the units, try a few practice tests and time yourself.
Correct every problem. For multiple-choice questions, simply look up the answer. If you got it wrong or guessed and got it right, look at the explanation. Write it down. If it doesn’t make sense to you, review what you have learned or ask a teacher for help. For free response questions, copy the exact code into an IDE such as Eclipse and run it. If there are any errors in the syntax or logic of the program, fix them to the best of your abilities. If you still don’t understand, look up a sample answer and write down what you did wrong. Even though this feels discouraging, writing your mistakes down will help you in the long run because it tells you want not to do.
Testing Strategies for the AP Computer Science Principles Exam
Section 1 (Multiple-Choice):
Use scratch paper for the “math” part. Spend no more than one minute per question unless it’s math-heavy or requires a lot of reading, such as traversing 2D arrays. For this type of question, spend no more than 3 minutes. If you don’t know how to do a problem, mark it. After finishing all the problems, go back and do the problems that you marked. Then check your work.
Break:
Don’t think about anything related to the exam. This will stress you out. Instead, take a snack break and walk around the classroom (if you’re able to).
Section 2 (Free Response):
Use scratch paper to do the math and plan the logic in your code with pseudocode. Spend 10-15 minutes on question 1, 20-25 minutes on question 2 and 3 each, and the rest of the time on question 4. If there is time left over, check your work using these questions:
Does my method have the required inputs and outputs?
Does the logic of my program fit with the example provided (if there is one)?
Overall, the AP Computer SciencePrinciples A exam requires much preparation and practice. However, this is not an excuse to stress yourself out. When the time comes, you will do an amazing job. Good luck!
Citations
https://fiveable.me/ap-comp-sci-a/faqs/5-ap-computer-science-a/blog/UdXHZl07jEiKPkm9bKpR
https://blog.prepscholar.com/how-to-study-for-ap-exams
https://apcentral.collegeboard.org/pdf/ap-computer-science-a-course-and-exam-description.pdf?course=ap-computer-science-a
https://apcentral.collegeboard.org/courses/ap-computer-science-a/course
https://apcentral.collegeboard.org/courses/ap-computer-science-a/exam
