Reflection and Mirror Images
Reflection and Mirror Images is a non-verbal reasoning topic where pupils work out what a shape or shaded pattern looks like once it is flipped across a mirror line. It appears in GL Assessment and CEM-style 11+ papers, testing whether a candidate can track exact distance from the line rather than judge the reflection by eye alone.
Method
- Identify the mirror line's direction first: vertical, horizontal or diagonal, since each type flips a different pair of measurements.
- For a vertical line, keep the row the same and swap the column to the same distance on the opposite side; for a horizontal line, keep the column the same and swap the row.
- For a diagonal mirror line running from top-left to bottom-right, swap the row number and the column number of each shaded cell.
- Check that every shaded cell keeps the same distance from the line after flipping, not just the one closest to the line.
- For real objects such as letters or arrows, notice that a feature at right angles to the mirror line reverses direction, while a feature running parallel to it stays the same way round.
- Rule out options that only slide the shape sideways without flipping it, or that flip along the wrong axis altogether.
Worked example
A grid has 3 rows and 3 columns. A single cell is shaded in row 2, column 1. A vertical mirror line runs straight down the middle of the grid, through column 2. Which cell is the correct reflection?
- The mirror line is vertical, so the row of the shaded cell does not change: the reflection stays in row 2.
- Work out how far column 1 is from the mirror line: column 1 is 1 column to the left of column 2.
- The reflection lands the same distance on the opposite side of the line: 1 column to the right of column 2, which is column 3.
- Final answer: the reflected cell is in row 2, column 3.
Practice questions
Try each question, then tap to reveal the answer.
Exam-style questions
Written in the style of a 11+ exam paper, with a full mark scheme.
A grid has 3 rows and 3 columns. Two cells are shaded: row 1, column 1 and row 3, column 1. A vertical mirror line runs through column 2. (a) State the row and column of each reflected cell. (b) Explain why the row numbers do not change during a vertical reflection. (3 marks)
A capital letter E stands next to a vertical mirror line on its right-hand side. State what the reflected letter looks like, and explain why it does not simply look like an ordinary E after reflection. (2 marks)
A single cell is shaded in row 2, column 3 of a 3 by 3 grid. The cell is first reflected in a horizontal mirror line running through row 2, and the resulting figure is then reflected in a vertical mirror line running through column 2. (a) Give the position of the cell after the first reflection. (b) Give the position of the cell after the second reflection. (c) Explain why the first reflection made no visible difference to this particular cell. (4 marks)
Free printable worksheet
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