My teacher gave us a homework It goes exactly like this why is the earth flat When his students answer the question he will prove them wrong How can I prove correct to him that it's an oblate spheroid?

Answer 1

Show him how the circumference of the earth from pole to pole (top to bottom) is shorter than the circumference of the earth at the equator. When an aeroplane is travelling further from you, it will disappear into horizon.

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It sounds to me like his intention is to hear arguments from the class that the world is flat so that he can counter the arguments with evidence to the contrary. He is taking the role that the earth is an oblate spheroid. I think he wants you to take the position of people centuries ago who did not have access to our current knowledge. If I have interpreted your question correctly, then why not join in the fun and really make him work at his proof. You could say things like:

• My experience of the world is that it is flat.
• I don't know how all those photographs were made, or how they might have been tampered with.
• I can only see so far and no farther because the surface is bumpy, not smoothe, and because the atmosphere sometimes obscures the view.
• If the world were not flat, wouldn't we slide off as we started going over the curve? (We both know this is silly, but what would the experience be of people in Medieval times?) If your teacher says something about gravity, you can ask him how he experiences people on the other 'side' of the world being pushed up, or is that just something he has to make up to support his belief in the Big Ball theory?
• If there is a large object hovering high in the atmosphere, will it always eventually come down to earth? "Yes", he will say. Isn't this evidence that the earth is flat? Otherwise the object would sometimes miss and go someplace else.

If your teacher doesn't have a particularly good sense of humor, you might want to go easy with some of this. Eventually you will have to admit (and do so graciously, because your teacher can take only so much of this) that you must accept as valid quite a few observations that you have not personally made. This is what a lot of science involves. On the other hand, healthy skepticism about everything is what causes science to advance. I'd love to hear how the lesson goes.