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A3 Slippery slopes and cans on the run

Can rolling down a ramp.

Students continue to explore gravity while also experimenting with how friction slows things down.

Activity A3: Slippery slopes and cans on the run [PDF, 291 KB]

How to use this activity

This is a hands-on exploratory activity which involves the students timing a can of food rolling down a ramp.

The amount of friction the can has is then varied by adding things like hairbands or socks (fine and more chunky varieties make a good contrast).

Discussion about keeping the height of the ramp and the launch point of the can the same each time will assist students to understand the need for a consistent method if their results are to have meaning or be compared to another group's results. It is easier to time if you do not set the ramp too high.

At some stage, introducing the terms “variables” (in this case the surface being rolled on) and “constants” (in this case the can, the ramp height and the launch position) may be appropriate. Depending on the ages of the students, recording of results can be done in a variety of ways.

This activity is adapted from Building Science Concepts Book 42: Marbles. Additional content support for teachers can be found in this book.

Book 42: Marbles: Exploring Motion and Forces (TKI - Science online)(external link)

Where it fits in the New Zealand Curriculum

Nature of science strand

Investigating in Science – ask questions, find evidence, explore simple models and carry out appropriate investigations to develop simple explanations (Level 3-4).

  • Science activities can be used to develop any of the Nature of Science sub strands.
  • Identify aspects of Investigating in Science that your students need to get better at or understand more fully.
  • Then frame your unit to be very clear about these things when you do them.

NZ Curriculum | Science achievement objectives(external link)

Capability focus

Gather and interpret data, use evidence.

The five science capabilities (TKI - Science online)(external link)

Contextual strand

Physical World. Explore, describe and represent patterns and trends for everyday examples of physical phenomena, such as movement, forces (Levels 3-4).

Big science idea

Gravity is a force which acts to pull objects.

Friction is a force between objects when they move over one another. It can be both useful and a problem.


  • Gravity is a force pulling objects toward the Earth.
  • The amount of friction which an object encounters will affect its speed and the distance it travels.
  • The less friction there is, the further an object will travel.

Capability concepts

  • It is important to keep some things the same (constants) so that we can reliably test what we are measuring (variables). 
  • Measurements are needed to describe our observations accurately.
  • There are similarities and differences in what we observe.

Possible learning objectives

The students can...

  • identify the things which need to be kept the same in their experimental trials (constants) and what they are going to change (variables)
  • use accurate measurements to make detailed observations
  • identify and describe patterns involving similarities and differences
  • compare trial results with other groups of students. Where there are differences, students can make statements/inferences about the reason for any differences
  • link gravity in this investigation to another experience of gravity they have had
  • describe what friction is in relation to their investigation and/or everyday life
  • make a statement about how friction effects speed.
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