The lovely little St Faith’s Anglican church built in the Maori village of Ohinemutu, reflects in the still waters of Lake Rotorua. Reflections occur often in life: you probably experience one every morning!
Mathematically, reflection is one of the isometries: transformations which preserve length (and angle). You might like to analyze how the reflection occurs in this photograph. Suppose I am standing facing the church, and seeing both the church and its reflection. Concentrate on the tip of the tower and its reflection. How do the light rays travel? Your explanation might involve two congruent triangles and a smaller similar triangle.
http://en.wikipedia.org/wiki/Reflection_(mathematics)
