I had an excellent experience on exactly this subject.
At my home airfield we were all getting ready to go home. Then we noticed a small Cessna just north of our field. We checked if we had any radio contact...no, there wasn't any, Behind that Cessna another, larger one flew just behind the first. We all knew there were thunderstorms to our west. The Cessna 152 made a smooth landing, the Cessna 172 also landed soon afterwards.
The "story": the Cessna 152 was a student on his first solo, He had already done 2 landings at his home field, but then the storms approached. His instructor (still on their home frequency) told him to start flying East, which he did. His father took the Cessna 172 and followed him. Neither of them had an air chart! oooops
Luckily he found "our" airfield, which is a very easy one. After they landed, we found some space in our hangar for the two planes and we decided that I would fly the C152 the next day, and my boyfriend of the time would fly the C172 back home.
The next day, our mechanic noticed that the C152 needed a new tire so he changed it and told me about it, then off we flew. We found their airfield, an American military one, we contacted their field and got permission to land, which we did. The instructor then flew us home in the C172. I must say, this event was quite fun, but I'll never forget it.
So, the biggest wrong doing of the instructor: letting the poor student try his solo's when extremely bad weather was expected. Neither the student nor his father had a proper air chart
They were lucky to find our field...there were others in the area but none as easy as ours
(no obstructions, etc.)
Anyway, lesson to learn: make sure conditions are good for solos and make sure they have proper charts on board ( and know how to use them).