T-GEM: Building a mental model of Tides

The BC Science Curriculum for grade 4 includes the Big Idea of “The motions of Earth and the moon cause observable patterns that affect living and non-living things”. To investigate the challenging concept of changing tides as it affects living and non-living things on Earth (due to Earth’s axis, rotation, orbit around the sun, gravitational pull of the Moon and lunar phases), the T-GEM model will be used to support student inquiry using tidal simulations and teacher guided strategies. In the T-GEM model, Khan emphasizes the importance of teacher actions that promote student inquiry (Khan, S., 2010), therefore, teacher guidance, as to when to use the technology throughout the process, is key to students generating relationships and evaluating patterns effectively in the creation and modification of their mental models.

Often, tides due to gravitational pull is a difficult concept for students, as it requires them to create an accurate scientific mental model of the role of the Sun, the Earth’s axis and the Earth’s orbit, which are not directly observable phenomena for students. The enhancement of a digital simulation, in conjunction with the cyclical Generate (G), Evaluate (E) and Modify (M) model should help enrich students’ involvement and engagement with scientific inquiry and provide opportunities to build accurate mental models of unobservable phenomena (Khan, S., 2007).


Tides – the influences of the Earth, Sun and Moon


Teacher Strategies Student Processes
Compile information Teacher background info on tides: BrainPOP video: https://www.brainpop.com/science/earthsystem/tides/



Students record what they know/ understand of tides from BrainPOP video. They fill in what they know of tidal changes on a diagram, including the Earth, moon and Sun in their drawing. Students share out their drawings.
1.     Generate Teacher limits variables in simulation for students (One earth day, Earth’s rotation, Earth’s orbit, Moon’s position).

Ask students to find patterns.

Ask students to proceed at each Earth day (24 hours).

Ask students to incrementally proceed and observe changes.

Ask students to compare tidal heights.

Ask students to explain in a group share-out of their findings.


Students interact with the EduMedia simulation: https://www.edumedia-sciences.com/en/media/97-tides.

Students repeat simulation for one Earth day (24 hours). In pairs, students generate patterns and relationships between Earth’s rotation and tide level; Moon’s position and tide level; Earth’s orbital position and tide level.

Students share-out their findings and what they predict for tides year-round.

2.     Evaluate Provide students with “spring tide” and “neap tide” scenario: greatest and least difference in tidal heights with video: Lunar and Solar Tides on Science Primer: http://scienceprimer.com/lunar-and-solar-tides

Ask why is there a change? Ask students to predict why this occurs.

Ask students to compare to regular tides. (Find new data over one Earth year.) “Are there other exceptions?”


Students observe video and simulation, paying close attention to when tide is at its highest and lowest.

Students interact with Lunar and Solar Tides simulation on Science Primer, focusing only on “Tidal height” throughout Earth days. Students make note of their predictions and compare with initial data.

Students record new data related to Spring and Neap tides.

Students evaluate tides over a year. Students discuss their findings with other groups.

3.     Modify Ask students to modify their relationships on a new drawing chart. Ask students to clarify their reasoning for patterns/relationships.

Prompt student explanations with questions during share-out.

Students re-examine their data, including Spring and Neap tides.

Students re-create their drawing, explaining the relationships of the Sun, Moon, and Earth’s orbit/rotation on tides in a drawing, digital sketch or physical model.

New models are shared out, explained and questioned by peers.

Technology Links:

Technology Links for T-GEM: Tides



Khan, S. (2007). Model-based inquiries in chemistryScience Education, 91(6), 877-905.

Khan, S. (2010). New pedagogies for teaching with computer simulationsJournal of Science Education and Technology, 20(3), 215-232.


  1. Hi Jocelynn,

    I have found that Brainpop has been a great resource over the years, and has been great with continually adding new videos to their database. I really like how you have included the two other resources as well, one for each of the generate, evaluate, and modify phase. By providing a differentiated approach through a variety of tech based applications, each student will inevitable take something different from these resources to add to their bank of knowledge. I also love your point about students creating a digital sketch, as this is something that I have found works really well with students beginning in grade 4 as they learn to consolidate their thinking. I wonder if you would also take students to the local beach if possible, and or would be able to use any live videos from local beaches.



    1. I love that so many teacher are using Brain Pop. It’s underused where I teach, and I think it’s a great tool to scaffold learners. It’s especially helpful for students with ADHD and English Language Learners. I find that students are so engaged with the cartoons and related activities. I love the hands-on learning you provide for your students. A great example of teacher-led and student-directed inquiry. Thank you for sharing.

      1. I agree BrainPOP is often underused. I myself find that I don’t maximize my use with it always. Since I teach in a French Immersion context, it can be a challenging but rewarding resource for vocabulary building. Although, having watched some of the videos in English, I think I might begin to incorporate the english videos when the content gets a bit too complex for them in French.

    2. A field trip to the beach is a fantastic place to learn! Although I was focusing on adding the tech piece to the T-GEM model, I would definitely consider a trip to the beach to examine the waves. Possibly a day trip where we can observe the tide level at low tide, and again at high tide. That would certainly make my second resource more meaningful, as it shows a boat moving up and down the dock. Something we could observe on our field trip. Thanks for the idea!

  2. Hi Jocelynn

    I like the fact that you discussed mental models. I spent many years studying the human body (digestive, circulatory, muscular etc) through books and movies. It was not until I was able to dissect and rhesus monkey that I could fully understand how all the different systems are connected.

    I wonder if students would fully understand changing tides as it affects unless they actually see the changes in front of them. This could takes years.

    A good next step might be to explain how or what your students do “during share-out”. What does the audience do while the group is sharing?


    1. Thanks for pointing out audience participation Christopher. Usually, I would have students try to sit quietly and “listen” to others speak out, but that is rarely effective and it certainly does not fit with the T-GEM model of having students actively evaluate their own understandings.
      I’ve used a couple of different methods in the past that might facilitate that by either having students “text” their friends their ideas on sticky notes. Or they could actually “text” ideas using a Padlet or TodaysMeet. Both platforms allow for free idea flow while they are viewing/listening to another student’s ideas. I imagine for it to be truly an effective alternative, like all things, there would need to be quite a bit of practice before hand.

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