Free Grade 9 Computer Science Worksheets with Answers

Grade 9 Binary Numbers

3A-DA-09

Converting between binary and decimal with place values 1, 2, 4, 8 … and adding binary numbers.

e.g. Write the decimal number 111 in binary.

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Grade 9 Hexadecimal

3A-DA-09

Converting between hexadecimal, decimal and binary, and reading hex colour codes.

e.g. Convert the hexadecimal number 31 to 8-bit binary.

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Grade 9 Bits, Bytes & Data Sizes

3A-DA-09

Converting between bits, bytes, KB, MB and GB, and working out file sizes and storage.

e.g. How many bits are in 2 bytes?

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Grade 9 Variables & Data Types

Recognising integers, floats, strings and Booleans, and how operators behave on each.

e.g. What data type is the value 65.6: integer, float, string, or Boolean?

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Grade 9 Tracing Code (Python)

3A-AP-15

Reading short Python programs with variables, if/else and loops and working out what they print.

e.g. total = 0; for i in range(1, 8): total = total + i * 1; print(total). What is printed?

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Grade 9 Tracing Loops

3A-AP-15

Tracing repeat and nested loops to find the final value or the number of times something happens.

e.g. total starts at 0. The loop repeats 3 times: total = total - 3. What is total at the end?

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Grade 9 Lists & Arrays

3A-AP-14

Indexing, slicing and changing lists, and finding their length and values.

e.g. nums = [27, 49, 37, 38, 32, 41, 14]. What is nums[3]? (Indexes start at 0.)

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Grade 9 Searching & Sorting

Counting the steps in linear and binary search and tracing bubble and selection sort passes.

e.g. Bubble sort (smallest to largest). Write the list after the first full pass: 32, 19, 41, 8, 24, 28

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Grade 9 Flowcharts

Following flowcharts with decisions and loops to find the output for a given input.

e.g. Flowchart: input x = 1. Is x > 5? If yes, output x − 8. If no, output x × 3. What is output?

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Grade 9 Boolean Expressions

Evaluating Boolean expressions with AND, OR and NOT, including comparisons.

e.g. What is the value of not (False and False) or False?

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Grade 9 Logic Gates

Working out the outputs of AND, OR, NOT and XOR gates and small logic circuits.

e.g. A circuit computes (A OR B) XOR C with A = 0, B = 1, C = 0. What is the output?

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Grade 9 Networks & the Internet

How networks move data: devices, IP addresses, packets and download times.

e.g. Which technology connects devices without cables using radio waves: USB, WiFi, or HDMI?

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Grade 9 Cybersecurity & Passwords

Password strength by counting combinations, spotting threats, and simple encryption.

e.g. A Caesar cipher moved every letter 3 forward. Decrypt: EBWH

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Grade 9 Functions & Return Values

Advanced

Tracing functions with parameters and return values, including functions that call other functions.

e.g. def f(x): return 2 * x + 2. What does print(f(f(2))) show?

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Grade 9 Algorithm Efficiency (Big-O)

Advanced

Comparing how the number of steps grows: O(1), O(log n), O(n) and O(n²).

e.g. What is the time complexity of this code: for k in range(11):; print(k)? Choose O(1), O(log n), O(n) or O(n²).

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Grade 9 Computing Challenge Puzzles

Challenge

Puzzles that stretch computational thinking: bit patterns, logic and clever counting.

e.g. A playlist app lets you switch each of 6 songs on or off. How many different playlists (including the empty one) are possible?

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