The Bible doesn't "teach" anything about the shape of the Earth. The Bible assumes the most prevalent cosmology at the time of the authors. They did believe in a flat earth, but the teachings in the Bible are theological, not scientific. God just didn't take the time to explain cosmology to the ancient world, probably because they would have been confused. Probably, we would be confused if God told us how the universe was really constructed right now...
http://drmsh.com/christians-who-believe-the-earth-is-really-flat-does-it-get-any-dumber-than-this/