Research indicates that many students do not develop proficiency in scientific practices, such as argumentation. The Framework for K-12 Science Education and the forthcoming Next Generation Science Standards emphasize eight practices that are key elements of K–12 science and engineering instruction, and one practice is “engaging in argument from evidence.” In Scientific Argumentation in Biology: 30 Classroom Activities, authors Victor Sampson and Sharon Schleigh present a framework for teaching students how to understand how an argument in science is different than an argument that is used in everyday contexts or in other disciplines such as history, religion, or even politics. The framework is illustrated here:

Strategies and Activities of Argumentation

To integrate argumentation into the teaching and learning of biology,  you can use a number of strategies. The book breaks down these strategies into three main ones:
1. The construction of a good argument that provides and justifies a conclusion, explanation, or some other answer to a research question. Examples of activities for teaching your students to generate arguments include Fruit Fly Traits, Evolutionary Relationships in Mammals, and Characteristics of Viruses.
2. The design of  activities or tasks that require students to examine and evaluate alternative theoretical interpretations of a particular phenomenon. Examples of activities for teaching your students to evaluate alternatives include Plant Biomass (photosynthesis), Cell Size and Diffusion (diffusion), and Healthy Diet and Weight (human health).
3. The writing of a refutational essay to allow students to explain why a common misconception is inaccurate and then explain why a scientific view is more valid or acceptable from a scientific perspective. Examples of activities for teaching your students to write a refutational essay include Misconception About the Nature of Scientific Knowledge (nature of science), Misconception About Bacteria (microbiology), an Misconception About Inheritance of Traits (genetics).
The teacher notes included with each activity provide specific ways in which you can supplement what you are doing in your biology class. Help your students move beyond expressing mere opinions when making their claims.
Other resources to aide your biology instruction include The Biology Teacher’s Handbook and Hard-to-Teach Biology Concepts. For additional NSTA resources on argumentation and discussion in science class, see “Engaging Students in the Scientific Practices of Explanation and Argumentation,” an NGSS-related article by Reiser, Berland, and Kenyon published in NSTA’s April 2012 journal issues, and the free chapter “Scientific Inquiry: The Place of Interpretation and Argumentation” from Science as Inquiry in the Secondary Setting.