My favourite part time job was running a school holiday playscheme for 5 to 11 year olds which I did every school holiday for three years after I left school. We used to do loads of sports activities and arts and creative activities and I loved to see the children enjoying themselves and doing fun stuff through the holidays. I think I might have enjoyed it more than the children I was looking after!
I have had loads of part time jobs during college and university, but mostly were just a means to an ends to get some money!
The one I enjoy the most I still do over the summer each year and it is voluntary. I am a supervisory teacher with a charity who run residential week long courses for secondary school pupils like you. They are aimed to get you involved in science and engineering and range from biomedical engineering, to nuclear, to computer science etc etc – there are loads and they are really fun! I highly recommend you give them a go!