# Variables required to model a given system

In an examination students will not be expected to identify more than four variables in a given system.

Let's answer this question by looking at a few different systems and imagining which variables might be the most impactful.

## a sports player[edit]

If I wanted to create a model of a sports player what variables might I choose? I want to choose a variables that are meaningful. Maybe:

- number of injuries
- age
- number of points scored
- number of games won
- number of games lost

I think these variables MIGHT help me model a sports figure.

## a country[edit]

Maybe I wanted to create a model of a country. The variables I choose might be related to what I want to do with my model.

- percentage of population with electricity access
- electricity - consumption
- electricity - exports
- electricity - imports

These variable are used from the CIA world factbook with gratitude. I wonder why they create models of EVERY COUNTRY ON EARTH?

## a car[edit]

I wonder how these variables might inform my choices about buying a car:

- total cost
- monthly average gasoline cost
- monthly repair cost
- monthly resale value

## Standards[edit]

- Identify the variables required to model a given system.