Flat earth

Good folks.The title is misleading and I apologize in advance.I am interested in the simplest scientific experiment that a layman can carry out in order to determine rough measures regarding the Earth's shape and size. Think high-school education or less, if possible.I have no religious agenda nor care to support/undermine any of them. I just want the simplest scientific methodology that would allow me to conduct the aforementioned experiments.Thank you all.Be well.

I'm afraid you misunderstand.My question has nothing to do with high-school. I simply wanted to provide an educational baseline.Now, please ask yourself. Do you know the Earth is round or do you believe it is round? Most people claim to "know" it when, in fact, they simply believe it.And anyone can believe anything.The only way to actually know something of this nature is to be in possession of a specific kind of methodology. In particular, scientific methodology.Yes, it is possible to Google this matter... in general. However, is there a layman's experiment that demonstrates the Earth is round? In my opinion, this is a question relevant in this kind of forum.