or "go on page 11"???
Go to page 11. Or "open your book on page 11" (I believe this is also an acceptable option, although I'm not sure about it being natural).
Please be aware that I'm neither a native English speaker nor a teacher.
I've learned here that we use 'at' when we want to instruct students to open their books:
'Open your books at page 3'
And "Open your book(s) to page 11" in BrE too.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.