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Year 7 · Summer 2 · Raid: Code for a Cause

Raid build: finish, test, improve

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What this lesson covers

Topic 11 Algorithms

KS3 Computing · An algorithm is a precise, step-by-step plan to solve a problem. Computational thinking turns a messy problem into one. Every algorithm is built from just three things: sequence, selection and iteration.

Programming Computational ThinkingCambridge Lower Secondary Computing 0860

You will learn to

  • Use another guild's testing to find problems in the game and the poster.
  • Give and receive feedback using two stars and a wish.
  • Fix the most important problems first, then test again.
  • Rehearse a two-minute presentation about the cause, the poster and the game.

Success criteria

  • I can give another guild two specific stars and one wish.
  • I can sort what testers found into 'breaks it', 'misses the success list' and 'nice extra'.
  • I can fix a problem and show it is fixed.
  • I can present my part in our two-minute presentation.

Key words

Say each word, then read what it means. Every one is in the glossary too.

Algorithm
Precise, ordered, finite steps to solve a problem.
Decomposition
Breaking a problem into smaller ones.
Abstraction
Ignoring detail that doesn't matter for the problem.
Sequence · selection · iteration
Steps one after another. First this, then this.
Pseudocode
Code-like writing for algorithms, without strict rules.
Trace table
Records variable values step by step to check logic.
Variable
A named place in memory that holds a value.

The explanation

Read it here, or open the study page below to go one step at a time with things to try.

Testing with another guild

Another guild plays your game and reads your poster. They have fresh eyes, so they see problems you cannot.

  • Play the game at least three times.
  • Try to break it: odd keys, edges, losing on purpose.
  • Read the poster from the back of the room.
  • Check that every image has a credit line.
  • Check each line of the success list: yes or no?

Feedback: two stars and a wish

A star is something that works well. A wish is one thing to improve.

Good feedback is specific. It says exactly what and where.

e.g.Example

Specific: 'The score is easy to see. I wish the litter fell more slowly at the start.' Not specific: 'It's good.'

★Remember

When you get feedback, say thank you and write it down. Do not argue. Decide later what to change.

Improve: fix, then test again

  1. List everything the testers found.
  2. Sort the list into three groups.
  3. Fix the first group first.
  4. Test again after every fix.
  5. Tick off the success list.
What testers foundGroupFix
The game never ends at 0 livesBreaks the gameIf lives = 0, say 'Game over', then stop [all v]
The poster heading is too small from the backMisses the success listMake the heading much bigger
A sound when you catch litter would be funNice extraOnly if there is time left
!Watch out

Do not start a nice extra while something still breaks the game.

The two-minute presentation

  1. The cause, and why it matters.
  2. The poster: its message and who it is for.
  3. A short demo of the game.
  4. One thing testers found, and how you fixed it.
  5. Who did what in the guild.
★Remember

Practise out loud with a timer. Two minutes goes very fast.

e.g.Worked example

Testers found three things. The litter falls through the bin. The beach photo has no credit line. The bin could be a cooler colour. What do you fix first?

  1. Litter falling through the bin breaks the game, so fix it first. Check the touching (Bin v)? block names the right sprite.
  2. The missing credit line misses the success list, so fix it next. Add title, author, source and licence.
  3. The bin colour is a nice extra. Change it only if there is time.
  4. Test the game again after the first fix, before moving on.

Study it

Open the study page and go one step at a time.

Topic 11 · Year 7

Algorithms

An algorithm is a precise, step-by-step plan to solve a problem. Computational thinking turns a messy problem into one.

Check yourself

One question at a time. The reason shows after each answer.

Saved on this device.