Refraction of Light and T-Gem Principles

One challenge for students is to understand the refraction of light.  For example, when a student observes a straw in a glass of water, the straw looks like it is bending. This is due to the properties of light, but this understanding can be fraught with misconceptions regarding how light behaves. Some interesting misconceptions about light may be that water does not reflect or absorb light but light can go through it, light always passes straight through transparent objects (without changing direction) or that light needs air to travel (Sampson & Schleigh, 2016).

Research notes that although light is an everyday phenomenon that we constantly observe, students often display learning difficulties and hold unscientific understanding on physics concepts of light wave (Srisawadi & Kroothkeaw, 2014). In addition, concepts of light such as its speed and wave length are removed from the range of perceptions of the human senses, and so optics instruction can be subject to interpretation, so there is a need for careful consideration in physics teaching process (Srisawadi & Kroothkeaw, 2014). Computer simulations can broach this divide. As noted, computer simulations can enhance generating relationships and allow students and teachers the opportunity to view trends, variables and visual representation  in more concrete ways which may lead to more accurate conceptual understandings (Khan, 2011).

In order to generate information about this phenomenon the educator can begin an open-ended discussion to find out current concepts about light. Questions such as:

What is light?

Where do you think light comes from?

How does light travel?

This will allow the educator to begin to understand what conceptions and misconceptions the students may hold about light and will also allow the students to begin thinking about the concept. As this discussion is occurring the educator can note responses on chart paper or interactive whiteboard so that ideas can be reviewed as the process of understanding continues. As an educator I would incorporate “accountable talk” which will allow students to defend their ideas and question others about their understandings. Examples of accountable talk would be statements like;

“I wonder why….?

“I see what you are saying (rephrase)”

“What you said made me think….”

Then as an educator I would facilitate a review of the ideas generated in the group discussion through referring and restating the list created by students. I would break this down further into “Our First Ideas about Light” and then create another section for questions we now have about light. This would be labelled “Our Questions about Light”. We would brainstorm some questions that we have. Then I would provide students with appropriate books and internet resources about light. I would also show them a model or a picture of a straw in a glass of water. The straw appears to bend and so I would ask them how they would explain the phenomenon. After they have a chance to read/view this information, I would ask them to work with a partner, independently or in a small group (provide choice) and to draw or create a clay model of their understanding of light.

We would then reconvene and compare our models. I would give students time to explain their models to their peers so that I could continue to assess possible misconceptions. At this point the students may begin to reformulate their understandings based on new learning from their peers. Then we would watch several simulations about light refraction. I would ask the students to consider their previous understandings by asking “Do you need to change your original drawing/model? Or “Do you think you need to modify your original drawing/model?”  Our new understanding would be discussed and a new category would be added to our discussion titled “New Understandings”.

Bending Light Simulations

Refraction in Water Simulation

Bending Light Simulation


Bending Light. (n.d) Retrieved March 1, 2017, from

Khan, Samia (2011).  New pedagogies on teaching science with computer simulations. Journal of Science Education and Technology 20, 3 pp. 215-232.

Refraction in water. (n.d.) Retrieved February 29, 2017, from

Sampson, V., & Schleigh, S. (2016). Scientific Argumentation in Biology [PDF file]. Arlington,Virginia. NSTA Press Book. Retrieved from
Srisawasdi, N. & Kroothkeaw, Supporting students’ conceptual development of light refraction by simulation-based open inquiry with dual-situated learning model. S. J. Comput. Educ. (2014) 1: 49. doi:10.1007/s40692-014-0005-y



  1. Hi Michelle,

    Can you share with us what age level this lesson on light was targeted at in your curriculum?

    I like your accountability talk and these are great questions to begin to initially probe students’ conceptions: Where do you think light comes from?

    In terms of evaluation within the T-GEM lesson, having students gather information from various sources is a way for the class collective to enrich what they know in the (evaluate phase). Evaluation of what students’ know may lead to students affirming, expanding, or disconfirming their original ideas. Sometimes, students will emerge with a plethora of ideas, and teachers will need to group or categorize some in order to pursue several targeted investigations (c.f We would brainstorm some questions that we have). Asking students to explain their ideas about what is going is key to all phases in T-GEM: I would also show them a model or a picture of a straw in a glass of water, especially when a discrepant event occurs: The straw appears to bend and so I would ask them how they would explain the phenomenon. The opportunity to model light using clay will begin to explore the particle nature of light. Broaching light as also a wave will promise to be an interesting discussion.

    What might be expected from students you teach in terms of the clay model?

    In my research, the E phase is most often missed when constructing and revising models in class. I am glad to see how this unfolds fully in your lesson. Thank you for this contribution to a challenging topic, Samia

    1. Thank you for your thoughtful questions and comments Samia. In consideration of the grade level, I was thinking primary level and did not have a specific grade in mind, I was attempting to think as an elementary educator and determine what would work for this age range of students. In consideration of what I believe they would gain by creating a model, I reflected on how using inquiry and allowing students to construct their ideas (either by drawing or modelling) their understandings can be a way for children to “show what they know” in a variety of ways, not just paper and pencil or orally. Often working through the process of creating a model will allow students to refine their understandings either through the process of building it or through sharing the model and interacting with others to refine the model. It also allows the students to become invested in understanding the concept. Much research shows that the construction of physical artifacts contributes to students’ understandings of science concepts and some of this research aligns with GEM principles. In one study, students built and tested a model and were given the chance to improve or optimize the model and then use it to explain concepts they were learning about. Through the process the researchers found that classroom learning environments that engage students in building activities help to enable the sharing of student ideas and that these ideas are critically and collaboratively shared which led to deeper understandings of the concepts explored (Sherman & MacDonald, 2006). In addition, the researchers found that students were more engaged when building the models as they were allowed to develop and try out ideas and imagine possibilities which allowed for the development of enhanced confidence and understanding by students (Sherman & MacDonald, 2006). Interestingly, students in this study were able to identify and describe key features of their model long after it was completed, which seems to suggest that building models allows students to retain concepts.
      When considering GEM and T-GEM I do not think creating models will necessarily create pathways to complete understanding of scientific concepts, especially in terms of refraction of light, as this is a difficult concept to explore and students may create models that do not represent this phenomenon accurately. This being said, the models are a point for discussion and the students can modify their models after the evaluation stage. In addition, the models provide a rich environment where students are working collaboratively to help explain a phenomenon and this is where they can test out ideas and begin to take ownership of their learning. It allows the educator to be a facilitator and to assess misunderstandings or further question students and as the research shows it creates an environment where the students are eager to explore the concepts. Finally, it is another way for students to demonstrate the process of learning and is a way to differentiate the learning of science concepts.

      Sherman, A., & MacDonald, L. (2006). Children’s perspectives on building science models. International Journal of Primary, Elementary and Early Years Education 34, 1. 89-98.

  2. Michelle,

    I love how you begin with the driving questions. Without that, what is the direction of the learning…and what is the point? I like to think of the driving question as the fuel of the rocket and the ‘accountable talk’ as the guidance system. The challenge after that is figuring out when you have reached your target…how can students identify that they have ‘gotten it’ without being told by a teacher?

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