Computer Science
Grade 2
20 min
The Missing Step
Identifying the missing step in a set of instructions.
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Define a 'bug' as a mistake in a program.
Explain that 'debugging' is finding and fixing bugs.
Identify a missing instruction in a simple sequence of commands.
Trace a short program one step at a time to find an error.
Add the correct block to fix a program with a missing step.
Test their program again after adding a fix.
Oh no! Your robot friend wants to build a tower 🧱, but it keeps stopping. What's the missing step?
We will learn how to find mistakes in our code. These mistakes are called bugs 🐞. Finding and fixing them is called debugging!
Real-World Applications
Fixing a recipe that tastes funny 🥣
Finding a lost toy in your room 🧸
Figuring out why your LEGO tower fell over 🏰
Giving a friend better directions t...
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Key Concepts & Vocabulary
TermDefinitionExample
Bug 🐞A bug is a mistake in your code. It stops the computer from doing what you want.You tell a robot to move forward twice, but it only moves once. That's a bug!
Debug 🕵️Debugging is like being a detective. You look for the bug and fix it.You look at your code and see you forgot one 'move forward' block. You are debugging!
Algorithm 📜An algorithm is a list of steps to do something. It's like a recipe for a cake.1. Get bread. 2. Get jelly. 3. Spread jelly on bread. This is a sandwich algorithm.
Sequence ➡️A sequence is the order of the steps. The order is very important!You must put on your socks *before* you put on your shoes. That's a sequence.
The Missing Step❓This is a bug where you forgot to add a step. The computer gets stuck.Your co...
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Core Syntax & Patterns
One Step at a Time
Read and check each block of code, one by one.
Don't rush! Follow your code's path just like the computer does. This helps you find exactly where the bug is hiding.
Act It Out
Pretend you are the computer or robot. Do each step yourself.
When you act out the code, you can feel when something is wrong or missing. It's like a practice run!
4 more steps in this tutorial
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Challenging
A character fails to get through a door. The code is: `1. Walk to door`, `2. Turn knob`, `3. Walk through door`, `4. Open door`. What is the most logical way to fix this bug?
A.Swap step 3 and step 4
B.Delete step 2
C.Put step 4 at the very beginning
D.Add a `Knock on door` step
Challenging
A robot is in a maze. The code is `REPEAT 10 TIMES: [Move Forward]`. It hits a wall after 3 steps. What is the BEST way to fix this so it works in ANY maze?
A.Change the code to `REPEAT 3 TIMES: [Move Forward]`
B.Add a `Turn Left` block inside the loop
C.Use a `LOOP UNTIL you touch a wall: [Move Forward]`
D.Make the robot smaller
Challenging
A program is supposed to count from 1 to 3, showing "1, 2, 3". Instead, the output is "2, 3, 4". What is the most likely bug?
A.The loop is repeating too many times
B.The program is skipping the number 1
C.The program is adding 1 to each number before it shows it
D.The program started counting from 2 instead of 1
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