Coding Algorithms

Overview

Lesson 8 of 18 in Innovate or Invent: Year 3–4. Students learn that an algorithm is a clear, ordered set of instructions, then create and test a short program using a block-based coding platform. The lesson follows a low-variance routine: explain, model, practise, test and reflect.

Learning intentions

Students will:

• Explain what an algorithm is and why instructions need to be in the correct order.
• Identify sequences, commands, events and repetition in a simple program.
• Create a short block-based program for an innovative solution or challenge.
• Test, find and correct an error in their algorithm.
• Work safely and cooperatively when sharing a device.

Success criteria

• I can describe an algorithm as a set of ordered instructions.
• I can arrange coding blocks to make something happen.
• I can predict, test and improve my program.
• I can explain how my program helps solve a small problem.

Curriculum links

• Designing and creating digital solutions that meet a purpose or user need.
• Representing and communicating ideas using digital systems and simple algorithms.
• Following, creating and evaluating step-by-step instructions, including sequencing and repetition.
• Collaborating respectfully, sharing responsibility and responding to feedback during a design process.

Lesson structure (45 minutes)

1. 0–5 minutes – Settle, display the goal and hook Open with the introduction and hook slides. State: “Today we are learning to give a computer instructions in the right order.” Ask: “What might happen if a robot receives instructions in the wrong order?” Students briefly share or point to a response. Show the visual timetable: listen, model, make, test, share.

2. 5–12 minutes – Teach the key ideas Use the coding concepts slides to introduce algorithm, command, sequence, event and repeat. Model a familiar algorithm, such as packing a school bag, and deliberately swap two steps. Students identify the error. Explain that computers follow instructions exactly and do not guess what we mean.

3. 12–18 minutes – Teacher model: predict before running Project the coding platform and use the worked-example slides. Build a short program in which a character moves, makes a sound or says a message when the start event occurs. Before running it, ask students to predict what will happen. Add one repeat block and model changing one command to improve the result.

4. 18–30 minutes – Guided programming challenge Give the four students roles: driver, navigator, checker and encourager; rotate roles halfway through. Distribute the algorithm planning and testing sheet. Students work in pairs, or as one group if only one device is available, to create a program for one challenge: guide a character to a goal, greet a user, or show one step in an innovative solution. Require at least four ordered commands, one event and one repeat or change.

5. 30–37 minutes – Test and debug Return to the testing and debugging slides. Students run their program, compare the result with their plan and record one success and one change on the worksheet. Prompt with: “What did you expect?”, “What happened?”, and “Which block could you change?” Students make at least one improvement and test again.

6. 37–42 minutes – Share and compare Each pair or the group demonstrates its program. Use the share-and-discuss slides to structure feedback: “I noticed…”, “The algorithm worked because…”, and “A next improvement could be…”. Emphasise that debugging is a normal part of designing a digital solution.

7. 42–45 minutes – Review and exit response Use the plenary slide. Students complete the final section of the worksheet or verbally answer: “An algorithm is…”, “One command I used was…”, and “I improved my program by…”. Revisit the learning intention and celebrate careful testing, not just a finished animation.

Resources

• Four tablets or computers with a child-friendly block-based coding platform available.
• Projector or interactive display.
• the Coding Algorithms slide deck.
• the algorithm planning and testing sheet.
• Headphones, if appropriate for the platform.
• Timer and clearly labelled device workspaces.
• Visual timetable displayed on the board.
• Optional teacher-prepared sample program for modelling.

Assessment

• Observe whether students can sequence commands, identify an event and explain the purpose of a repeat block.
• Check the worksheet for a planned sequence, prediction, test result and recorded improvement.
• Use the final responses and demonstration to assess whether students can explain how debugging improved their digital solution.

Differentiation

• Provide a reduced choice of three or four large, clearly labelled blocks; model one step at a time and keep the visual timetable visible.
• Pair students deliberately and use the roles of driver, navigator, checker and encourager to support attention, communication and turn-taking.
• For students needing additional support, provide sentence starters, read worksheet instructions aloud and allow verbal or pointing responses. Offer headphones and a quieter workspace where helpful.
• For extension, students add a second event, a condition such as “if,” or a second repeat, then explain how the change makes the solution more useful.