Do I grow smaller when I'm father away?

David made an interesting observation during a morning walk into the forest. 

Pointing toward the end of the path he said, "Look the path gets smaller near the end."

"So does that mean that you will get smaller if you stand at the end of the path?" asked his teacher.

"Yes, I will get smaller too, " he replied confidently.

"How can we find out?" she asked.

"Just measure me, here (pointed to where he was standing) and there (pointing toward the end of the path).

Then next day they returned to the forest with a metre stick. The teacher measured David both at the beginning of the path and near the end.

She showed David his height on the metre stick at both points.

"What happened?" she asked. "Did you get smaller at the end of the path?"

"No I'm still the same size,' he replied.

"So do you think the path got smaller or is it also the same size?'

"No the path isn't smaller. It just looks that way from far away!"



The teacher measures David at the beginning of path.



The teacher measures David near the end of the path.





David sketches the path.



As Dsvid works on his drawings her gains a better understanding of depth.