Give students this fun, authentic activity to help them understand the concept of bartering and trading. Each student gets a scoopful of trail mix (I made my own, with pretzels, peanuts, M&Ms) and I just 10-12 pieces of special candy (I used Airheads). It became a matter of chance who got those special pieces. I used these to introduce the concept of scarcity, and how it can raise the value of something. I explained that it was up to the students to decide which piece of food they thought was most valuable, and I modeled a trade (eg. I will give you 6 pretzels for 3 M&Ms -- why do you think I offered him 6 pretzels instead of 3?) At the end of the activity, you can even tie it back to Math by asking them to "count up" their inventory, by giving them a conversion chart, and asking them the value of their inventory in US Dollars.