When I did my work experience I did two weeks in a primary school first and got a card and box of chocolates off the teacher. Then I did two weeks in an office and got a cheque for €100. Actually it was probably £100 ... God I'm old

Looking back that was pretty damn generous, but then again it was the office of a construction supplies company at the height of the Celtic Tiger.
Most people in my class got something, e.g. a voucher or small gift, however no one expected it and there was certainly no one giving out if they didn't get anything. I'd say wait til Christmas, and if you're impressed with her work and attitude then it would be nice to give her some little thing.