In the days/weeks leading up to this lesson, set up a marble run in the classroom (see the List of materials for details). Allow students time and opportunity to interact with it and make observations about what happens.

To begin this lesson, replay the passing game played in Lesson 1, and re-enacted in Lessons 2 and 3. Explain to students that this time, when they play the game, they will only pass the objects by rolling. Before they roll, they need to select an object they think will roll well and explain why they selected it.

Model the movement of rolling objects with students in various ways, for example, by rolling arms/hands over each other, or by rolling an object.

Make an obvious mark on a large ball and watch the mark as the ball rolls, so students can see that the ball is ‘going around and around’. Compare it to the movement of sliding something across the floor or a table, and discuss how rolling and sliding are different.

Define the movement of rolling in simple terms, for example: something turning over and over again, or going around and around as it moves.

Optional: If developmentally appropriate, you might also discuss the difference between spinning and rolling: spinning tends to occur on the same spot, while rolling involves moving along a surface.

Discuss students’ experiences and observations interacting with the marble run in the lead up to the lesson.

Examine and discuss what is happening in the cartoon found on the Marble run concept cartoon Resource sheet. Discuss students’ recent experiences using the marble run (that was set up prior to this lesson), what they’ve learned, and any problems they encountered.

Pose the questions: What might make it easy for something to roll down a ramp? What might make it harder? Record students’ ideas in the class science journal.

Next, pose the question: Does the type of ball used change how far the ball will roll down a ramp?

Explain to the students that scientists ask questions, test their predictions, plan and carry out tests to find things out. Tell them that they will be working like scientists to find out if changing the object being rolled will affect how far it will travel.

Show students an appropriate number of different spherical objects. The number of objects you select will be determined by the readiness of your students to deal with complexity. The more objects you look at, the more complex the comparisons and investigation will be.

Give students the opportunity to make observations about each object and together construct some comparative statements about the differences between them, like the materials they are made from, their weights, or their shape. For example: The cricket ball is heavier than the tennis ball, The marble is made of glass and the ping pong ball is made of plastic, or The baseball is more round than the kiwifruit.

Using the demonstration copy of the Rolling investigation planner Resource sheet, as a class complete the Predict and Reason sections of the PROE (Predict, Reason, Observe, Explain), with students nominating which object they think will roll the furthest and why they think that. You might make a tally of the number of students that think each object will roll the furthest, then record the reasons of a few students. You can support students reasoning by making connections between their previous experiences of playing different games/sports or playing with the marble run.

Next undertake the investigation as a whole class.

First, with or for students (as appropriate) list in the class science journal:

1. What will be changed in the investigation: the object being rolled.
2. What will be measured at the end of the investigation: the distance the object rolls.
3. What will stay the same in the investigation: the height of the ramp, what the ramp is made out of, how we measure how far each object rolls. 

Show students the streamers or other method for measuring the distance, and explain how measurements will be taken:

1. The end of the streamer will be placed at the top of the ramp next to the item to be rolled.
2. After the item has been rolled, you will unravel enough of the streamer to reach where the object stopped, and cut the streamer off.
3. The length of the streamer will show how far the object rolled.

Emphasise that the ramp gives all the things the same, fair start—just place and then let go! You might also model the difference between simply letting the item go and giving it a ‘push’ start, and discuss why this would not be fair.

Roll each item you have selected for testing, and measure the distance rolled as described above.

Make a simple column graph for students by placing the streamers next to each other.

Together, complete the Observe and Explain sections of the PROE by recording which object rolled the furthest, in reference to the graph, and why students think this happened. Students’ explanations may not be scientifically accurate—the purpose of the activity is simply to provide opportunities for them to experience this type of scientific analysis.

Referring to the definition of rolling earlier in the lesson, present students with the statement: Round things roll better because it’s easier for them to turn over and over again. Ask students if they agree with this statement or not, and why. Consider if the data on the graph proves this statement—did the objects that were ‘more round’ roll further than the ones that were ‘less round’.

Discuss why it’s easier for round things to roll over and over. You might look at how corners of square objects ‘catch’ on the ground and stop objects from rolling, or how round objects have less contact with the ground as compared to square ones. Demonstration using spherical and cuboid objects is a good way to establish this.

Ask students to name the materials that the objects were made of, and if they think the materials had any impact on the object’s ability to roll. You might draw attention to texture here as well, for example that a tennis ball is ‘furry’ whilst a ball-pit ball is smooth. Discuss and record any relevant ideas for reference in the next lesson.

Ask students if they have any other questions they might like answered as a result of the investigation.

Reflect on the lesson

You might:

• ask students to think about what other factors may influence the movement of a ball rolling down a ramp.
• add to the class word wall any vocabulary related to rolling, fair testing, investigations, etc.
• re-examine the intended learning goals for the lesson and consider how they were achieved.
• discuss how students were thinking and working like scientists during the lesson. Focus on looking at data to provide evidence.