I agree with all the above posters. Doing training is a completely legitimate reason to enter Canada as a temporary business visitor. Such travellers do not require a visa or any prior authorization if they are travelling on a US passport. Be honest and clear and carry documentation to support your purpose of travel.

Never lie to border officials - if you are caught, you could be banned from Canada. Here's the official Canadian government page covering your situation:

http://www.cic.gc.ca/english/visit/business-who.asp