Parol Evidence. Mountain Stream Trout Co. agreed to buy "market size" trout from trout grower Lake Farms, LLC. Their five- year contract did not define market size. At the time, in the trade, market size referred to fish of one-pound live weight. After three years, Mountain Stream began taking fewer, smaller deliveries of larger fish, claiming that market size varied according to whatever its customers demanded and that its customers now demanded larger fish. Lake Farms filed a suit for breach of contract. (See page 387.) The first group will decide whether parol (outside) evidence is admissible to explain the terms of this contract. Are there any exceptions that could apply? A second group will determine the impact of course of dealing and usage of trade on the interpretation of contract terms. A third group will discuss how parties to a commercial contract can avoid the possibility that a court will interpret the contract terms in accordance with trade usage