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.

To help high school students develop a deeper understanding of energy and matter flow in biological systems, a key goal of the Next Generation Science Standards (NGSS), we have designed a series of inquiry-driven modules that experimentally explore photosynthesis in the context of carbohydrate partitioning. Carbohydrate partitioning refers to the distribution of photosynthesis products from source organs, such as leaves, to growing or storage tissues. These cost- and time-effective modules help students develop a more integrated understanding of how energy flows from light into leaves before moving outward to other parts of the plant and ultimately into other organisms. Our approach of teaching carbohydrate partitioning along with photosynthesis greatly expands the number of NGSS core ideas and cross-cutting concepts in an integrated manner, empowers students to see how photosynthesis and carbohydrate partitioning are central to their existence, and provides a rich platform for experimentally addressing questions related to photosynthesis, crop production, global climate change, plant physiology, and the carbon cycle.

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.

Our society is currently having serious debates about sources of energy and global climate change. But do students (and the public) have the requisite knowledge to engage these issues as informed citizenry? The learning-progression research summarized here indicates that only 10% of high school students typically have a level of understanding commensurate with that called for in the Next Generation Science Standards . The learning-progression research shows how most students fall short of being able to trace matter and energy through carbon-transforming processes such as photosynthesis, respiration, and combustion that are at the center of analyses of energy use and global climate change. We discuss the more typical types of understanding that students develop and their implications for teaching.

We present a guided-inquiry biology lesson, using the plant–rhizobium symbiosis as a model system. This system provides a rich environment for developing connections between the big ideas in biology as outlined in the College Board’s new AP Biology Curriculum. Students gain experience with the practice of scientific investigation, from designing and conducting experiments to making claims based on the data they collect. We include one example of a piloted classroom experiment that can easily be modified to test a variety of interesting ecological and evolutionary hypotheses.

In many labs on photosynthesis, the presence of starch in leaves is used as an indirect indicator of photosynthetic activity. Students do starch tests on leaves from plants that have been kept under a variety of conditions in order to check parameters for photosynthesis. The starch test can also be used to enable students to discover differences between plants that use C 3 or C 4 photosynthesis.

I wrote a rap song to explain the process of photosynthesis to my students.