Computer Science study guide
This guide is designed to help you understand the core ideas that commonly appear in introductory college Computer Science courses. Read the explanation, follow the example, then try the practice questions without looking back. The goal is to understand the reasoning—not just memorize an answer.
Course requirements vary by school and instructor. Use this as a learning and review resource alongside your assigned textbook, lectures, and instructor guidance.
Algorithms
Concept: An algorithm is a finite procedure for solving a problem; correctness and efficiency both matter.
Worked example: Binary search repeatedly halves a sorted search space, giving logarithmic search time.
Remember: Focus on the central relationship in algorithms, define the important terms, and connect each step to the evidence, rule, formula, or process being used.
Common mistakes: Common mistakes include memorizing algorithms without understanding when it applies, skipping units or definitions, and giving an answer without showing the reasoning that supports it.
Practice it
- Explain algorithms in your own words.
- Use the lesson idea to create or solve one new computer science example.
- What is one common mistake a student should avoid when working with algorithms?
Data structures
Concept: Data structures organize information for efficient access and modification.
Worked example: A stack uses last-in, first-out order; a queue uses first-in, first-out order.
Remember: Focus on the central relationship in data structures, define the important terms, and connect each step to the evidence, rule, formula, or process being used.
Common mistakes: Common mistakes include memorizing data structures without understanding when it applies, skipping units or definitions, and giving an answer without showing the reasoning that supports it.
Practice it
- Explain data structures in your own words.
- Use the lesson idea to create or solve one new computer science example.
- What is one common mistake a student should avoid when working with data structures?
Programming fundamentals
Concept: Variables, conditionals, loops, functions, and data types form the foundation of programming.
Worked example: A loop can repeat a calculation for each item in a list instead of duplicating code.
Remember: Focus on the central relationship in programming fundamentals, define the important terms, and connect each step to the evidence, rule, formula, or process being used.
Common mistakes: Common mistakes include memorizing programming fundamentals without understanding when it applies, skipping units or definitions, and giving an answer without showing the reasoning that supports it.
Practice it
- Explain programming fundamentals in your own words.
- Use the lesson idea to create or solve one new computer science example.
- What is one common mistake a student should avoid when working with programming fundamentals?
Object-oriented programming
Concept: Objects combine state and behavior; classes define reusable structures for creating objects.
Worked example: A Student class might store a name and grades and provide a method to calculate an average.
Remember: Focus on the central relationship in object-oriented programming, define the important terms, and connect each step to the evidence, rule, formula, or process being used.
Common mistakes: Common mistakes include memorizing object-oriented programming without understanding when it applies, skipping units or definitions, and giving an answer without showing the reasoning that supports it.
Practice it
- Explain object-oriented programming in your own words.
- Use the lesson idea to create or solve one new computer science example.
- What is one common mistake a student should avoid when working with object-oriented programming?
Complexity
Concept: Big-O notation describes how resource use grows as input size increases.
Worked example: A single pass through n items is typically O(n); nested full passes are often O(n²).
Remember: Focus on the central relationship in complexity, define the important terms, and connect each step to the evidence, rule, formula, or process being used.
Common mistakes: Common mistakes include memorizing complexity without understanding when it applies, skipping units or definitions, and giving an answer without showing the reasoning that supports it.
Practice it
- Explain complexity in your own words.
- Use the lesson idea to create or solve one new computer science example.
- What is one common mistake a student should avoid when working with complexity?