I recently bought a book Phenology – the study of times of recurring natural phenomena especially in relation to climate. Its an interesting read with lots of useful activities for students and though it is rather focussed on organisms found in the UK it has great teaching ideas for observing the affects of climate change.
I then found links to websites that involve observing Nature’s calendar, inspiring students about the natural world and helping make them make a meaningful contribution to the climate change issue and become a citizen scientist. Visit http://www.naturescalendar.org.uk/secondary to register with the project (UK only), its free.
I live in Canada so I quickly came across http://www.naturewatch.ca/english/.
A short search gave me this for Australia http://www.earthwatch.org/australia/news/headlines/news_story5_14mar081.html
For the USA, http://www.usanpn.org/.
Check out whether there is an organisation in your country, if not perhaps you could ask your students to follow that which is done on other websites etc, looking for landmark organisms etc.
Though I have one eye on the Ecology and Conservation option, I think that phenology provides excellent opportunities not just at Grade 11 / 12 but throughout the whole school to engage students in direct outdoor observations and learning of the environment around them.
Perhaps, someone reading this may wish to take this further, contact schools around the world through the IBO OCC (?)website and set up a student phenology network where data can be compiled and shared from schools on all continents to look at trends, analyse data etc. Just a thought….