Season 5, Episode 8: Arya tells story of how she would reinvest her daily profits, first for a second bucket to bring to the market, then for a cart. This allowed Arya to bring more goods to the market and make great profits. Standard economic models show that with an increase in capital – which is one of the factors of production – one should see an increase in production/sales/profits.
To teach this concept in the classroom, click here for a lesson plan