I am researching a company for my class. I am supposed to identify the depreciation method in use.

How do I do this? I've searched through their annual report and they don't explicitly say.

You will probably have to call company HQ and ask to be put in touch with someone who can help you. I suspect that you will be told that the depreciation method depends upon the asset class and when the depreciated item was purchased. The rules are always changing. This excerpted article may be helpful:

http://goliath.ecnext.com/coms2/gi_0199-2310359/Technical-note-new-depreciation-rules.html