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Grade 6 · Technology, computer science and digital literacy · 25 minutes

Unit 1 · Instructions and Digital Decisions · Lesson 1 of 2

Write an Algorithm Someone Else Can Follow

Write and debug an unplugged algorithm that moves a marker through a grid.

Mr. S Teaches · Original starter mini-lesson · MS6-TECH-01 · Elective / rotation; availability varies

Learning objective

Produce an ordered set of unambiguous instructions that a partner can execute to reach a specified grid location.

Before you begin

  • Read a simple grid; count whole-number steps.

Gather your materials

  • Paper
  • Pencil
  • Small paper marker

Language to know

Algorithm
A finite sequence of precise steps for completing a task.
Debug
Find and correct a problem in instructions or a program.
Input
Information an algorithm receives before or during a task.

Understand the concept

An algorithm must say enough for another person or machine to act without guessing. Draw a 4-by-4 grid numbered across columns 1–4 and upward rows 1–4. Start at (1,1), facing toward increasing row numbers. “Go up, then right” is ambiguous because distances are missing. “Move forward two squares; turn right; move forward two squares” reaches (3,3). The starting location and facing direction are inputs; changing them can change the result even when the steps stay the same. Test instructions before assuming they work.

Teach it step by step

  1. Draw the grid, label the starting location and facing direction, and mark the target (3,3).
  2. Model the three precise instructions from the explanation and record the marker’s position after each move.
  3. Write instructions from (1,1) to (4,2). Give them to a partner who follows them literally without filling in missing steps.
  4. Organize a short instruction sheet with headings for inputs, ordered steps and a test result. Revise one ambiguous phrase based on the test.

Make the thinking visible

Worked example or model response

Inputs: start (1,1), face increasing rows. Steps: move forward one square; turn right; move forward three squares. Test: (1,2), then turn in place, then (4,2). The turn changes facing, not location.

Guided practice

Test the draft “Move forward; turn right two squares.” Identify two ambiguities and rewrite it to reach (3,2) from the stated start.

Independent practice

Choose target (4,4). Write an input section and numbered instructions using forward moves and turns. Have a tester trace them, record the final location and revise your explanation if needed. Explain why the input section matters.

Quick assessment

Your algorithm works from (1,1) facing upward but fails when the marker starts facing right. Does that prove the written steps contain a bug? Explain.

Answer key & assessment criteria

Answers and teaching guidance

  1. Guided: The first move lacks a distance and “turn right two squares” confuses turning with moving. One correction: move forward one; turn right; move forward two.
  2. Independent: One valid solution to (4,4) is forward three, turn right, forward three from (1,1) facing increasing rows. The sheet must clearly identify inputs, ordered steps and a recorded test; equivalent routes are acceptable.
  3. Quick check: Not necessarily. The new facing direction changes an input. Either restore the specified input or revise the algorithm to support the different starting condition.

Look for: Credit a clear tested route rather than the shortest route. No device, account or programming language is required.

Make it work for your learner

More support

Use arrows and numbered move cards. A learner may direct a partner to record the algorithm and read it back before testing.

Extension challenge

Create two different algorithms to the same target and compare number of moves, number of instructions and ease of checking.

Selected contributions · Official sources

Standards connections

Subject-content alignment not yet verified

Supporting Common Core connection

W.6.2.a

Common Core · Grade 6

Organize a technical explanation with headings and ordered steps.

Read the official standard ↗

The instruction sheet practices organization within informative writing. It is an unplugged introduction, not verified computer-science content-standard coverage.

Source and mapping checked 2026-11-04. This mini-lesson contributes selected skills; it does not claim full attainment.