Find out why pedagogical content knowledge is vital in teaching chemical bonding

Models of different types of chemical bonding including diamond and salt on a table in a classroom. Behind a teacher speaks to the high school students.

Source: © ArtSvetlana/Shutterstock

Use ball-and-stick models to introduce the concept of covalent bonding

Chemical bonding is a vital topic. And it is challenging, particularly for new teachers. Teaching bonding begins early in many curriculums and links to many later theories. It must be addressed often and in different contexts, with appropriate pedagogical tools. This presents a significant challenge to trainee teachers.

A recent Chemistry Education Research and Practice (CERP) article presents a literature review on the knowledge teachers need to teach chemical bonding. Additional evidence is presented from several Dutch teacher educators regarding their pedagogical content knowledge (PCK) around the topic.

Why is PCK so important?

PCK is a combination of the content and pedagogical knowledge needed for teaching specific topics. Teachers develop it with experience. Enacted PCK (ePCK) is specific knowledge and skills used by a teacher to achieve particular student outcomes. Personal PCK (pPCK) is an individual’s knowledge and expertise in a subject area, resulting from cumulative personal experiences and contributions from students and peers. Collective PCK (cPCK) is the knowledge held by a group of people, partly developed through professional conversations.

The authors state the importance of cPCK to trainee teachers and teacher educators, who play a key role in the formative experiences of the former. The most commonly cited components of PCK in the review are knowledge of: students’ understanding, instructional strategies and representations, assessment, and curriculum.

Effective assessment requires a range of formative and summative approaches to support students further their understanding

Knowledge of students’ understanding is particularly crucial, as they often bring misconceptions from prior learning. Knowledge of instructional strategies (eg group learning, concept mapping) and representations (eg models, illustrations, simulations) allows teachers to help students develop an understanding of concepts and the relationships between them. Appropriate representations support students in bridging macroscopic and submicroscopic levels, and influence their ability to use structure-property relationships. Effective assessment requires a range of formative and summative approaches to support students further their understanding.

Teaching tips

  • Use a test such as the bonding representations inventory before teaching to identify the students’ prior knowledge. Particle theory is a crucial foundational topic. You may find the Review my learning worksheets on particle model and bonding useful to check prior knowledge and identify misconceptions.
  • Introduce the principle of chemical bonding based on electrostatic attractions before first teaching metallic bonding, followed by ionic bonding, then covalent bonding.
  • Teach ionic, polar covalent and non-polar covalent bonding as a continuum based on electronegativity differences.
  • Use structural formulas and ball-and-stick models when introducing covalent bonding. Beware of the models’ limitations and the misconceptions that may arise from their use (eg bonds are rigid entities, atoms have colour, atoms of different elements are the same size).
  • Avoid the use of anthropomorphic language such as ‘atoms want a full outer shell’; instead, focus on energy and stability as the basis of bonding.
  • Get students to work in groups to investigate the properties of materials, classifying their macroscopic properties. They should consider the submicroscopic properties. Dynamic representations such as animations and simulations are effective tools to use in bridging understanding between macro and submicro levels.

The importance of research and experience

The study aimed to bring together insights from research and experience to support teacher education. The literature review itself will interest those who want more in-depth insights. Eight key insights were identified linking to eight guidelines for teaching to address challenges. The insights included the fact that chemical bonding concepts are essential in many other domains, and that textbooks and teachers do not always use evidence-based teaching sequences.

Teachers should take students’ difficulties with bonding into consideration when planning lessons, especially as misconceptions can occur. The study also suggests that models and representations are considered critically to identify their characteristics and limitations.

The study involved nine teacher educators and contains valuable insight on the their extensive pPCK. Analysis found that four of the guidelines were identified by the educators: prior knowledge, strengths and limitations, applicability and micro-macro. However, the other four guidelines were not identified by most participants.


T H H van Dulmen et al, Chem. Educ. Res. Pract., 2023, DOI: 10.1039/D2RP00049K

David Read