Reason 1: As the lizard uses only two legs for movement, the exposed surface area to conduct heat from the hot sand is smaller than that of the snake which requires its entire body to be in contact with the hot sand when it is slithering. As such, the lizard will absorb less heat from the hot sand and its body will expend less energy trying to keep cool.

* Note: Don’t think any further elaboration on the biological processes involved with keeping the body cool is required for the primary school syllabus.

Reason 2: As the lizard’s two legs are the only parts in contact with the sand during movement, it needs to overcome less frictional force as compared to the snake which has its entire body in contact with the sand when it is slithering.