Over the last few weeks, we have been classifying things in our science lessons. We have been doing quite a lot of collecting things, and then breaking them into groups. We have classified rocks, plants, and random stuff we have gathered from the back yard. In our latest class, we took this idea to the point of defining a species.
The easiest working definition of a species is that it is a group of individuals which can potentially interbreed to produce viable offspring. Just trying to explain the definition to a six year old was something of a challenge, but I think we got there. My four year old missed it.
Of course, most living things are not aware of this definition, and so in practice, the lines can get a bit blurry. Although we didn’t push this idea to its limits, we did get as far as discussing different breeds of dogs, and subspecies of birds.
What I wanted to do was describe how a single species fits into a tree of life which describes all living things. I wanted to pick a bird as an example. Partly this was because they are easy to identify, and partly because birds are always in the background when we walk around outside, so I thought it would be a good way to make the boys pay attention to what is around them.
I asked the boys to pick their favourite bird. Initially, they chose a Kookaburra, but when they saw all the other birds in that family (Halcyonidae) they changed their mind to a Buff breasted paradise kingfisher. Its a prettier bird, but for the purpose of the exercise, it makes no difference.
We decided it was a living thing, and then set about classifying it into smaller groups. First kingdom, then phylum, class, order, family, genus and species. I was trying to impress on the boys that the more steps two living things have in common, the closer they are going to resemble each other.
It all started to get a bit complex, and most of what I was saying probably went over their heads. As long as they are asking questions though, I generally figure that too much is better than not enough.
While I was talking, my oldest boy drew his own tree of life. Tanysiptera is the genus name he has written from right to left on one side of his drawing. For those with keen eyes, you might notice the two species names from that genus written inside his kingfisher – sylvia and galatea. As a point of interest, Tanysiptera sylvia is the buff breasted kingfisher we were looking at.
Everyone was a bit worn out by then, so we went for a slow walk around the block. We took our bird book with us. In about twenty minutes, we had identified a dozen different bird species.
Although I find the actual book easiest to use for identification, we also have electronic copies in our phones/ ipods. The great thing about the electronic version is that they have recordings of all the calls. We spent the rest of the lesson listening to the different calls of the various species we had just identified.
The best nature studies are the ones which are right on your doorstep.