I have discovered a great resource for Y4. Veterans Affairs Canada publishes an educational kit for WW1 and WW2. You can order them free from their website, www.vac-acc.gc.ca or call 1-877-604-8469. WW1 is titled, Canada & The Great War 1914-1918. WW2 is titled, Sacrifice, Achievement, Legacy: Canadians & The Second World War 1939-1945. The videos included may still only come in that format, and not DVD.
The Usborne books recommended by TOG don't even specifically mention Canada participating, I guess we are lumped in with Britian.
The curriculum is recommended for grades 7-12, but the website had some info. for younger grades under Youth & Educators. Click on the animals in the war link to read stories narrated by animals.
Where do you find the educational kit on the site?