**Session Author: **James Tanton

You are brought to a crime scene. You are told that a thief just made off with a bag full of diamonds, escaping on a bicycle. You come across a pair of bicycle tracks in the snow, no doubt made by the fleeing thief. But which way did the thief go? Just by looking at the shapes of the tracks, can you determine which way the thieving cyclist went: left to right or right to left?

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**Strategies:**

Work backwards, Wishful thinking**Topics:**

Geometry, Problem solving**Styles:**

Kinesthetic element, One rich problem**Mathematical Practices:**

MP4, MP5