Most TA, RA are only offered to graduate students, because These smart students (Canadians or foreign students) are selected by professors, What is A(assistant) means?, It means they will do a lots of work, that is salary, not GRANT. 本地学生这边交大笔学费, Most of them are undergraduate students. Do you know what are different between Undergraduate and graduate education?. There are some universities giving Phd students free of tuition, you know why? Because University pay less and get more. In some universities, undergraduate students (must be top) can apply for TA( or RA) job and get salary by working for professors or departments)