It is of paramount importance to be able to differentiate between various angiosperms in olympiads. Not only classification, but also anatomical structure is needed to know. So below you can find a brief introduction to monocots and dicots.
Next, underneath you can find quite a good slide show about differences between monocots and dicots.
Take a look here at various plants cross sections.
Here you can find almost all major plant family floral formulas and more.
Finally, below in the presentation I compiled the most important cross section pictures of monocots and dicots.
Big thanks to http://biology.clc.us.edu/.