Ask Mendel's Mother

Sorting into Groups

"My son has asked you to sort out Dr. Theimer's folio of images and notes into different groups. This is called "Classification".

"To complete this task, you need to do three things:

you must decide what groups you intend have in your final system,
organize these groups so that they nest, small ones inside larger ones,
and
you must then look at each organism (in the folios of images) and decide where to put each creature.

"Groups first. If I was doing this task, I would only make two groups, (incidentally, each of these groups is called a taxon in science, and the plural is taxa). So I am creating two taxa.

I would call them Taxon A; - Large Creatures and Taxon B; - Small Creatures.

I have just devised a Taxonomy, which is basically a set of groups, and some test, or criterion, on which I could base my decision to put a specimen into one group or another.

For example, a small creature, like a sparrow, would go into the 'Small Creatures' group, while a large creature, like an elephant, would go into the 'Large Creatures' group.

"Then the Classification (or 'putting things into groups'). Now I have my groups I can take each creature in Dr. Theimer's folios, and carry out the 'test' or 'criterion'. I would measure each creature and if it was smaller than 30 centimeters, it would go into the 'small' group, and if it was larger than 30 centimeters, it would go into the 'large' group.

"My job is done, now it is your turn....

"First, look at all the creatures in Dr. Theimer's folios. Make some notes as to what each creature is, and anything special about it.

"Next, try to think of a 'group' that is unambiguous. The moment you have decided this, you actually have two groups (those that belong in this group and those that don't). Try putting some of Dr. Theimer's creatures into these two groups, and see how easy it is. Ask yourself, do all of these creatures fit easily into these groups, or are there some creatures left over that don't really fit?

"You should start with only two or three groups at this first level.

Then, try again. Take all the creatures in one of your groups (such as the 'Large Creatures' group I devised above, and see if you can think of 'sub-groups' that fit into this first group. For example, all my 'large' creatures could be further divided up into those with fur and those without fur. A large snake would be in group 'Large Creatures' and in the sub-group 'No Fur', whereas a horse would also be in 'Large Creatures' but would be in the second sub-group 'Has Fur'.

"Finally, go through the entire list of Dr. Theimer's creatures, putting them first into the major groups, then into the smaller sub-groups, and even into smaller groups still.

"List all your creatures this way,

Elephant: Large creature; Has fur;
Sparrow: Small creature; Has feathers;

Elephant: Taxon A; Taxon C;
Sparrow: Taxon B; Taxon E

Then send your list to my son. He is waiting to hear from you!"

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