Mark has no choice in the matter of going to school. This would represent a command economy, where economic resources are owned and controlled by the government. Like the people in command economies who have no control, Mark has to go to school whether he likes it or not.
The classroom: Mixed economy
However, when Mark gets on the bus, he chooses.This would represent a market economy. In a market economy, economic resources are owned and controlled by the people. Like the people in market economies who have the control, Mark has control over where he gets to sit on the bus.
The lunchroom: Freedom of choice
In Mark's class, chalk boards are still the board of choice. This would represent traditional economy, where goods and resources are produced the way they always have been and the country does not really participate in world economics. Like traditional economies, Mark's classroom still uses the traditional chalk boards and does not participate in the updating of boards to a new one.
School supplies: Private property
Mark has some choice in what classes he takes, but some are mandatory. This best represents a mixed economy, where command and market economies are combined. Similar to how the government nor the people have full control over economic resources, Mark nor the school has full control over the classes he takes.
When Mark goes to lunch, he has a wide variety of food choices and can pick whichever he prefers, and this represents freedom of choice. In capitalism, the freedom of choice is someone being able perform an action selected from at least two different options, unconstrained by external parties. Freedom of choice is beneficial because people have the freedom to choose without being told what to choose.
Mark's school supplies are owned by him and only him, and this represents the principle of private property. In Capitalism, private property is owning, using, or disposing things of value. Private property is beneficial is that people can do what they want with it, and because the government can't take it away because only the people own it.