Provide the students with a blank piece of paper. Ask them to draw and label three circles: one to represent the sun, one to represent Earth and one to represent the moon. (Note: Do not give any further instructions at this stage - the point of the exercise is to draw out the students' prior knowledge about the relative sizes of the three celestial bodies.)
Once the students have finished, ask them to hold up their drawings for their classmates to see. Ask guiding questions, such as:
- What do you notice about your classmates' drawings of the sun, Earth and moon?
- Why did you draw the sun, Earth and moon in the way that you did?
- Which drawing do you think is the most accurate and why?

Show the students three spherical objects to act as the sun, Earth and the moon. In terms of relative sizes, a basketball could be used for the sun, a grape could be used for Earth and a dry kernel of popping corn could be used for the moon. Through class discussion, encourage the students to match the correct object to the correct celestial body.
Watch the Relative Size of the Earth, Moon and Sun video on YouTube. Ask the students to pay particular attention to the animation at the end of the video which depicts the relative sizes of the sun, Earth and moon.

Show the students the cut out sun from The Relative Distance From the Sun to Earth teaching resource. Ask the students to suggest what size the Earth might be at this scale. After a few suggestions have been made, show the students the cut out Earth from the resource. Explain to the students that they are going to conduct a demonstration to model the relative distance between the sun and Earth (if they were scaled to these sizes).
Take the students outside to the pre-chosen area of the school grounds. Stand at one end of the space, holding the model sun. Ask the students to move away from the sun, until they think they are the correct distance away (relative to the scale). Explain that the student closest to the actual distance will be proclaimed the winner!
Allow the students time to move their chosen distance away from the sun. Once all of the students have decided on their position, secure one end of the 65 foot piece of string to the model sun and place it on the ground. Walk the piece of string out to the 65 foot point. Explain that this distance represents the 93 million miles between the actual sun and Earth.

Return to the classroom. Ask the students to revisit their drawings of the sun, Earth and moon from the tuning in activity. Encourage the students to make alterations to their drawing, or to use the back of their piece of paper to redraw their circles, based on the knowledge obtained during the lesson.