We started the experiment.

First of all we made trout. We wrote numbers horizontally and alphabet vertically.

I placed an eraser in accordance with it.

By the way, we used the "grapes" to make trout.

Place four mirrors on the parabola and look for the focus with the eraser shown there.

For your reference…

So I thought ...

If we put an eraser in a focus, we must see an eraser in every mirror

Like this↓

This is the opposite pattern
We put the eraser in the place where it seems to be in focus and saw it with our eyes.

There was one concern point…

This is "close to the focus", so it is not very accurate.
Next we examined the focus. Just like the way of the contens page.

So we thought about increasing the scale.

I tried to enlarge the parabola