T-GEM and Earth’s rotation


Challenging Concept:


The concept that I choose was one that my grade 4 class struggled with early on in the school year.  Understanding the lunar cycle, phases of the moon, along with the tilt of the earth’s axis and its impact on the various seasons was a challenge for them. I used various demonstrations with a globe, flashlight and pictures on the projector.  When they completed an extension activity afterwards, many of them still couldn’t explain how those things worked.


3 Step T-Gem cycle


  Discuss the moon and Earth’s gravity and rotation
Generate Demonstrate the rotation of the Earth using a model around the Sun.

Use a flashlight to shine on various parts of the and Earth to show where light would hit and various times of the year and day. Ask questions about where the students think it is cold/hot, daylight, nighttime

Evaluate Allow students to create their own diagrams of the Earth’s rotation and demonstrate how that impacts the various seasons.
Modify Ask students to consider their original ideas then consider how the various shapes of the moon are impacted by the rotation around the Earth



I found a website the models lunar phases and provides students with a few different vantage points with regards to positing on the moon and what that would look like on earth based on the different times and days of the year. You can see the sun rise and fall as the clock moves throughout the day, the moon’s position around the earth change, as well as the calendar year moving through each day.





  1. We do phases of the moon and lunar cycles in Grade 6 hear in the UAE, I think that the activity that you presented was simple enough that even my students that struggle would be able to do this and comprehend. Maybe you could have the students write their reflections and present them to the class (or to each other) in the Modification section? Thank you for sharing.


  2. Tyler,

    I think this topic benefits greatly from the simulation since it is very difficult to accurately reproduce the phases of the moon using commonly accessible light sources in a classroom. I liked how you use a dynamic real-life demo to initiate the topic, which helps to locate student thinking towards the general topic of the phases of the moon.

    However, the demo quickly reaches its limitations and the simulation then takes over to show the finer details. I particularly like the person on the Earth to show just where they are in Earth’s rotation and how the sun and moon would be seen.

    I’m curious how this could be extended for further investigation. Perhaps the students could sketch what would be seen on a fictional planet with two moons? A clip from Star Wars showing Tattooine and a discussion on how it has more than one moon would be a neat way to start that topic.

  3. Tyler,

    Thank you for sharing this very interesting simulation. The concept of lunar phases in relation to the rotation of the earth is difficult to visualize, describe, and understand without a model – hands-on or technology-based. You include both in your lesson!

    After previewing your simulation, I’m wondering if your T-GEM could consist of several cycles since there seems to be several big ideas being explored simultaneously: moon phases, tilt of the earth, seasons, day/night. I definitely like all of the various aspects delivered through the simulation, but wonder if one topic at a time should be addressed, each with a T-GEM cycle.

    In regards to the moon phases in the simulation, for me it would have been helpful visually to have a constant moon in the corner of the left main box gradually waning and waxing as the moon orbits the earth. While the moon phases are shown in the top right corner box, I found it a bit difficult to follow, but that may just be my brain. 🙂

    Thank you for sharing. I think there is some interesting potential!

  4. Hello Tyler,

    This is a very challenging concept and even after instruction, many students will revert or report their alternative conceptions, as you share: “When they completed an extension activity afterwards, many of them still couldn’t explain how those things worked. Sometimes children still report that the seasons are caused by the earth being far or closer to the sun, for example.
    Simulations can potentially help with this complex concept. I am glad to see that the simulation from the highered site has a pause time on it. Relatedly, what other affordances from your perspective does this simulation have for your lesson at this age group? What might be some conceptual issues that emerge as a result of viewing this simulation independently?

    Thanks for your input,

    PS. Bill Thornburgh writes an article on the earth-based perspective that might be of interest.

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