Moist skin helps in respiration. A think film of water is formed on the surface of frog, into which the atmospheric O2 gets dissolved and ultimately diffuses into the blood vessels underlying the...
In most species, the nostrils are placed on top of the head, so a frog is able to breathe while it's body is almost completely submerged under water. That way enemies cannot detect the frog easily.
well my child what you are asking is a very good question and it angers me that your teacher did not teach you this but the frogs uncle teaches the frog about boy parts (like the penus) and girl...