How it works
A bug is a mix-up in the steps. Bo does exactly what the steps say, so look in the steps, never at the robot.
Run the program one step at a time, and watch for the step where Bo goes off.
The bump can show up after the mix-up, so check the cards before the bump too.
Change just one step, and run it again to see whether the fix worked.
Worked examples
Finding the bump
- Maya's seven cards are: forward, forward, forward, turn left, forward, forward, forward.
- Bo walks three steps along the bottom, and card 4 turns him to face the top.
- On card 5, his next forward runs into the rock.
- The bump shows at card 5.
A taste of the worksheets
These are some of the questions on the sets. The printable sheets have more and an answer key.
- True or false? Starting again from nothing throws away cards that already work.
- Which one does not help find a bug? 👣 run it one step at a time / ⏩ only check the card that bumped / 🔍 find the step that goes off
- Which one helps find a bug? 🌪️ change every step at once / ↩️ check the cards before the bump too / 🗑️ start from nothing
- Which one does not help find a bug? 🔍 find the step that goes off / 👣 run it one step at a time / 🙈 ignore the bump and hope
- Which one does not help find a bug? 👣 run it one step at a time / 🗑️ start from nothing / ✏️ change just that one step
Words to know
- bug
- A mix-up in the steps.
- debug
- To find a bug and fix it.
- step
- One card of the program.
- run
- To make the program go.
Watch out for
- Do not blame the robot. Bo does exactly what the steps say.
- The mix-up may come before the bump, so check the cards before it too.
- Change just one step at a time, so you can see which change helped.
- Do not change every step at once, and do not ignore the bump and hope.
Try it
Bo bumps on card 5. Could the mix-up be on card 4?
Yes. The mix-up can come before the bump, so check the earlier cards too.
Why run a program one step at a time?
It shows the step where Bo goes off. Watching each step shows where the program stops doing what you want.
Maya slides the turn card one place later. How many forwards come before the turn now?
4. The cards become four forwards, a turn, and two forwards.
Is it quicker to start again from nothing, or to find the one step that goes off?
Find the one step. Starting again throws away steps that already work.
For grown-ups
Ask a grown-up to say three steps, one at a time, like forward, forward, turn. You are the robot and do exactly what they say. If you end up somewhere odd, go back through the steps one at a time, find the one that went off, and fix it together. Then swap jobs!
Play the Mission: say three steps one at a time, like forward, forward, turn, and let your child be the robot who does exactly what you say. If they end up somewhere odd, go back through the steps one at a time, find the one that went off, and fix it together. Then swap jobs.