Carbon dioxide (CO 2 ) is a colorless, odorless gas that makes up a small fraction of Earth's atmosphere. Despite its inconspicuous nature, CO 2 plays an integral part in sustaining life on Earth, a part that is largely unknown or underappreciated by the general public. We present a set of activities designed to help students overcome the most common misunderstandings about CO 2 , from its sheer existence as a mass-containing molecule to its complementary roles in photosynthesis and respiration. Through these activities, students will be able to apply their knowledge to real-world phenomena, including weight loss and global warming.

Carbon dioxide (CO 2 ) is a colorless, odorless gas that makes up a small fraction of Earth's atmosphere. Despite its inconspicuous nature, CO 2 plays an integral part in sustaining life on Earth, a part that is largely unknown or underappreciated by the general public. We present a set of activities designed to help students overcome the most common misunderstandings about CO 2 , from its sheer existence as a mass-containing molecule to its complementary roles in photosynthesis and respiration. Through these activities, students will be able to apply their knowledge to real-world phenomena, including weight loss and global warming.

The role of the electron transport chain, its associated proteins, and carrier molecules can be difficult for introductory biology students to understand. Role-playing activities provide a simple, active, cost-effective method for demonstrating and comprehending complex biological processes. This role-playing activity was designed to help introductory biology students learn the role of the electron transport chain in the synthesis of ATP. The activity can be completed within a single class period and, when combined with a post-activity writing assignment, can enhance student understanding of how the electron transport chain functions.

Undergraduate introductory biology students at the university level often struggle to trace movement of matter and energy through catabolic and anabolic processes in biological systems. A sequential guided simulation of cellular respiration and photosynthesis provides students an opportunity to actively model and visualize matter transformation and energy accumulation and degradation through the movement of molecular and energy “game pieces.” The activity was designed to help students generate a simplified outline of these two highly complex processes, while reinforcing the principles of conservation of matter and energy. My students participated in this activity during peer-led review sessions in an undergraduate, introductory, majors biology course (ca.150 students in 18 SI sessions over two semesters), but instructors could also easily adapt it for use in small lecture or laboratory classrooms, introductory cell biology, physiology, and ecology courses, or with high school students.

Students often struggle to understand the complex molecular systems and processes presented in introductory biology courses. These include the Calvin cycle, the Krebs cycle, transcription and translation, and DNA replication, among others. Traditionally, these systems and processes are taught using textbook readings and PowerPoint slides as lecture aids; video animations have also become popular in recent years. Students tend to be passive observers in many of these methods of instruction, relying heavily on “memorization” learning techniques. To address this, I developed an active-learning intervention called “molecular sculpting” in which students construct two-dimensional or three-dimensional versions of an assigned molecular system or process, complete with representations of proteins, chromosomes, electrons, protons, and other molecules (depending on the system). The value of this learning activity was measured in five class sessions in an introductory biology course during the 2014–2015 academic year. Pre- and post-class written assignments showed that students were often able to describe course concepts more completely after sessions in which sculpting was used, compared with sessions without sculpting. Molecular sculpting is a unique, hands-on activity that appears to have significant learning gains associated with it; it can be adapted for use in a variety of K–14 biology courses.

This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular respiration produces ATP. The activity works best as a supplement after you have already discussed the electron transport chain in lecture but can be used prior to instruction to help students visualize the processes that occur. This demonstration was designed for general college biology for majors at a community college, but it could be used in any introductory college-level or advanced placement biology course.

Using a design-based research approach, we developed a data-rich problem (DRP) set to improve student understanding of cellular respiration at the ecosystem level. The problem tasks engage students in data analysis to develop biological explanations. Several of the tasks and their implementation are described. Quantitative results suggest that students from the experimental class who participated in the DRP showed significant gains on cellular respiration posttest items, and students from the control class who participated in a non-DRP task showed no significant gains. Qualitative results from interviews and written responses showed that students from the experimental class progressed to deeper “levels of achievement” in cellular respiration. The data-rich tasks promote student understanding of cellular respiration, matter transformation, decomposition, and energy transformation – all goals recommended by the Next Generation Science Standards.