Today builds on previous lessons. Pupils will create a mirror image: they’ll follow code to draw a shape on one side of a vertical line, then reverse the steps (opposite order and direction) to reflect it on the other side. The core idea is symmetry—reversing precise moves produces a matching mirror shape.
One marker per pupil
Mirror worksheet: vertical line down the centre; numbered dots forming a half-shape on one side
Open by framing pupils as robot artists. Remind them that a robot doesn’t invent pictures—it follows code exactly. Today, they’ll use code to draw a picture on one side of a line and then mirror it by reversing the steps (opposite order and direction).
Set the tone: precise, one-step-at-a-time drawing. Emphasise that if something looks off, you’ll pause, check the last step together, and correct it—just like real programmers debugging.
Start with a quick discussion.
Ask: “Have you heard the word symmetry before? What do you think it means?”
Then invite examples: butterfly wings, leaves, faces, snowflakes, reflections in water, hearts, stars, some letters (A, H), shapes like squares and circles.
Highlight that in each case there’s a line you could draw so both sides match like a mirror.
Now do a fast board demo to make it concrete:
Draw a vertical line of symmetry. On the left side, draw a simple half-shape (e.g., half a heart or half a house outline).
Then show how to mirror it: Finish the outline and ask, “Does the right side match the left?”—naming this as symmetry.
Open the Mirror Robot – Half Picture interactive on your classroom screen. Explain that the left half will be drawn by following on-screen steps (one move per line), dot-to-dot. As you advance through the steps, have the class call out the move (e.g., “Right!” “Down!”) and watch the line appear on the board.
Keep a steady rhythm—pause after each corner to check the cursor is on the correct dot. If something looks off, rewind one step and fix it together (quick mini-debug). By the end of this sequence, the class should have a clean half-picture on the left side of the mirror line—ready for the next step, where you’ll mirror it on the right.
Open the Mirror Robot interactive on your screen. The left half of the picture is already drawn; pupils must code the robot to draw the right half so the whole image is a perfect mirror.
Explain the goal: “Your program should mirror the left side exactly—same shape, same distance from the centre line, just flipped.”
Pupils add arrow steps in the game to join dots on the right side, then press Run to see if their code draws the missing half.
Model the mirror rule briefly: use the same steps in reverse order and flip each direction (up ↔ down, left ↔ right). Encourage pupils to build a few steps, run, check alignment, and debug—fix just the first place it goes wrong, then try again.
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