What is the purpose of trading? What trade items are important? Objective Students will be able to identify: • What the explorers wanted in exchange for the trade items • Where and how the explorers obtained supplies outside the area where Euro-Americans had settled. • Which trade items were the most important once they reached the lower Columbia region Background The expedition members knew they could not bring everything with them they would need for such a long trip. Along the way they would need to buy food, information, guide and interpretation services and even transportation, such as ca Duration: 90 Minutes.