Several boys were using blocks and tracks to build a road system for their cars. Very wisely they all agreed they would need a petrol station to refuel their vehicles and tried to figure out where to put it.

“It needs go here so my car get in.” One child suggested.

“But my bus can’t get through there!”

this was followed by “an’ your cars blocking the track now!”

On hearing this debate, Mrs J suggested looking at how real petrol stations worked on the computer but the childre...