When you are flying a pattern around a field with a 10 mph breeze you have to be aware of ground speed and air speed.
If your plane needs a minimum air speed of 15 mph to generate lift then on the up wind section of the pattern you need to be doing a minimum ground speed of 5 mph for the wings to create lift
(5 mph forward motion + 10 mph wind = 15 mph airspeed)
conversely on the down wind section your ground speed will need to be a minimum of 25 mph
(25 mph forward motion - 10 mph wind =15 mph airspeed)
So as you can see there is quite a large difference between how fast the plane would look between the up wind section and the down wind section. This is a common beginners mistake and its hard to figure out exactly why your plane just seemed to fall out of the sky.