Activity Idea - Classify This!
Grab 10 note cards or scrap paper and head outside. Write down one natural item or animal that you see on each card (bonus points if you draw a picture of it!). When you've filled up your cards, take a look at them and think about how you'd group them together. Would you choose to group your items by size, trait or color? Could you come up with a system that would maybe group them by more then one category? When you're finished, do some online searching to see how the animals on your cards are actually classified.
Watch This - Intro to Taxonomy
Another great video about classification and how it works.
Read this - Redefining taxonomy
Daniel mentioned in the video how classification is always changing, scientist find new DNA evidence to link species together or apart, and new species are found regularly. All this makes taxonomy very hard and quite fluid. Take a read at these two articles for more: Study Doubles the World's Number of Birds and Hello! Mountain Gem.