The phases occur because the Sun lights up different parts of the moon as it circles around the Earth. The phase visible to us depends on the position of moon, in relation to the Sun and the Earth.
When the moon is directly between the Sun and the Earth, we cannot see it at all because no sunlight falls on the side facing us. This is the new moon phase. It takes the moon about three and half days to move from one position to the next. In position 1, we cannot see the bright side of the moon. This is a new moon which is very difficult to see. We see a half moon in position 3, since we can see equal parts of the dark and bright sides of the moon. In position 5, we see the whole bright side of it. This is a full moon.
(i) In which part of the sky would you see the full moon in the evening? (ii) In which part of the sky would you see the crescent moon in the evening? 
