Your contract isn't a requirement. However your letter of employment must state all the information required in the document checklist, including employment duration, hours, pay, title, and your job duties.
If you letter doesn't have this information, you will need to provide it (whether in the contract or another document).
Make sure you're supplying everything required in the checklist. It is always safer to also supply the optional documents, as the assessment of your work experience is the central reason the CEC class was created in the first place.