Get some extra cards now – before you’ve lost the one you had and need it in a hurry. Keep one on your boat and in your wallet and your dinghy safety kit.
The online course is directly based on this handbook – both approved by Transport Canada. Having a copy would be very helpful to refer back to after the course. And since the quizzes and final test for the online course are “open book” you might find this to help you focus on what you don’t know.