Match each 2×2 matrix to the transformation it performs on the plane.

• $\begin{pmatrix} 0 & -1 \\ 1 & 0 \end{pmatrix}$ → Rotation by 90° counterclockwise
• $\begin{pmatrix} 1 & 0 \\ 0 & -1 \end{pmatrix}$ → Reflection across the x-axis
• $\begin{pmatrix} 2 & 0 \\ 0 & 2 \end{pmatrix}$ → Uniform scaling ×2
• $\begin{pmatrix} 1 & 1 \\ 0 & 1 \end{pmatrix}$ → Horizontal shear

The columns-as-landed-axes trick decodes any matrix at sight: rotations swing both axes, reflections flip one, scalings stretch them, shears slide one along the other. Every 2D game engine and graphics pipeline is built from exactly these four moves.