Children in a car
During a car trip children can be enjoyed with mathematical concepts.
They can observe the following things.
A turn to the left or right.
More difficult are
A straight line.
S-curve with an inflection point.
Bend at its sharpest or strongest curvature.
Northernmost point (or other direction).
Point closest to the sun or moon.
In hilly or mountainous landscape possibilities are extensive.
The road is horizontal, climbing or descending.
Sometimes horizontal and vertical events happen simultaneously.
The steepness increases, decrease or remain the same.
Greatest slope up or down; inflection point.
Peak or valley.
Pass and saddle point (in the direction of a top valley).
If you drive in a bend, try to keep an eye on a tree trunk.
It moves relative to the background.
You'll see when you pass the tree,
the direction of movement of the tree reverses relative to the background.
It moves 'retrograde'.
In the same way, the temporary backwards motion of the planets
relative to the star background is explained.
Because the speed of the planet is not as great as the pace of the
Earth, the direction of the line Planet Earth is always changing.
The planet reaches a reversal point when the earth goes straight to it or
when the earth moves away from it straightly.