Organizations and individuals have been ranking science schools or their programs for years. In the US, a whole industry has arisen focused on the business of ranking universities and colleges, including undergraduate science schools (e.g., The Gourman Report, US News & World Report, World Science & National Institute). In Canada, however, there are no specific rankings focused exclusively on undergraduate natural and applied science programs.
MacLean's Magazine, however, does conduct an annual ranking of Canadian universities for their "undergraduate experience," and The Globe & Mail also publishes their "University Report". In addition, the National Sciences and Engineering Research Council ranks science schools on amount of research grants awarded.
Therefore, although indirectly, Canadian undergraduate science schools and programs are indeed ranked! How then should these rankings be interpreted? First, the ranking reports often come with detailed data to support conclusions, and while data collection may be criticized, the editors of these reports usually make an effort to ensure that statistics are comparable. So the reports can be used by you to compare institutions, schools and programs on the basis of the data provided.
Second, the statistics that come from the rankings can also suggest topics that need to be studied in more detail. For instance, if you find that a high percentage of students participate in a co-op experience and that few opportunities are in western Canada, you might want to explore during a school visit why few students go to this region of the country.
All university rankings have one other thing in common: they are a list of institutions, schools and programs. Scanning the list might suggest a choice that you had not considered or perhaps even heard of. Used this way, the rankings can help expand your list of institutions, schools or programs that can then be researched in more detail.
However, you should never judge a school or program based on its ranking alone. Rankings are important, but there are other factors that need to be taken into consideration. Institutions and schools that are less prominent may have a program that suits your needs better than any nationally ranked schools. Lesser known regional institutions and their schools can also be a good choice if you wish to remain close to home while undertaking your studies. Often times, these institutions and schools have the strongest relationships with local industries and employers. Once you have accumulated this information, you can create your own natural and applied science school and program rankings.