@dalehileman,
As always, your knowledge is quite fragmentary, Dale.
There's no such thing as Hock School (except, obviously the Saw Swee Hock School of Public Health, Singapore).
The phrase you needed was: I
ch weiß nur, was ich im Gymnasium gelernt habe.
The previous posters were right, Dale, English language is quite easy to learn, compared to many other languages.