Debugging

Lesson 6 - Year 5

Learning Intention

  • I can test and debug my programs

Introduction

Buggy ask and respond script with a trailing space in the answer

Start with the script below. Alter the script for 'yes' to include a space (or, if you want to make it easier, a full stop after yes). Ask children to predict what the code will do when it runs and you enter yes or no.

Teacher Input

Ask children to observe what Ohbot does closely when the code runs. Run the script. What does Ohbot actually do? How is it different to what we want?

Model going through the code line by line. Ask children to explain line by line in pairs, describing what each block does.

Get children to work in pairs to come up with possible solutions to make Ohbot respond to the answer. Run children's code suggestions. Explain that they can adopt this approach to debugging their own code.

Activities

1.

Children open up Ohbot projects they have written this term. Which work and which could be improved? Can they debug their programs to fix them?

Extension

Can children add extra code to their programs to improve them?

Plenary

Evaluation of the Ohbot project. Children to complete the following feedback.

Ohbot project evaluation feedback sheet
Ohbot image

Key Points

  • An answer that looks correct can still fail to match if it contains an extra space.
  • Comparisons with the `=` operator match the text exactly, punctuation and spaces included.
  • Predict, run, then compare what happened with what you intended.
  • Read code line by line to isolate where the behaviour diverges.
  • The same debugging approach works on any of your own projects.

Need Help?

If you're stuck on any part of this lesson, check out these resources:

Ohbot