Olympiad

https://en.wikipedia.org/wiki/International_Science_Olympiad

Helper
http://olympiadhelper.com/

Train
http://www.sofolympiadtrainer.com/

Tester
http://olympiadtester.com/

Science
http://www.sofworld.org/

Maths
https://www.imo-official.org/

Tube
https://www.youtube.com/results?search_query=Olympiad

Slides
http://www.slideshare.net/search/slideshow?searchfrom=header&q=Olympiad