Rolling marbles II

Rolling marbles II

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about fair testing.
Follow the instructions below and then answer the questions that follow.
Instructions
  1. Find a place where there is a carpet and smooth floor beside each other, and set up your two ramps so they are even. They should both have the same slope.
  2. Place the marble at the top of Ramp 1.
  3. Let the marble go (do not push it).
  4. Place a red sticky dot where it stops.
  5. Repeat this 10 times, each time putting a red sticky dot where the marble stops.
  6. Place the marble at the top of Ramp 2.
  7. Let the marble go (do not push it).
  8. Place a sticky blue dot where it stops.
  9. Repeat this 10 times, each time putting a blue sticky dot where the marble stops.

Question 1Change answer

a) What do you notice about the pattern of red and blue dots?

Question 1Change answer

b)  Complete the sentence by choosing the right word in the gap.
 "A marble rolls further on a roughsmooth surface."

Question 1Change answer

c) Look carefully at the smooth floor and the carpet. Why do you think the marble rolls further on one than the other?

Question 1Change answer

d)  Why is it fairer to roll the marble quite a few times for each test?
Task administration: 

This task can be completed with pencil and paper or online.

Materials for each group:
a marble; one ramp (a plank of wood works well), or two ramps the same length, material and slope; a rough and smooth surface, e.g., carpet and vinyl floor; red and blue sticky dots; flashcard with the question for investigation.

  • This activity should follow the principles of fair testing, i.e.; both the ramp and marble should stay the same, while the surface at the bottom of the ramp is different. It is preferable that the two surfaces be beside each other so children can easily compare the differences in distance travelled.
  • Display and read the question, "Will a marble roll further on a carpet or a smooth floor?" before students begin the task.
  • Rolling marbles assesses planning a fair test in this context, and could be used before students do this task.
 
Level:
3
Curriculum info: 
Science, Investigating in science, Physical World
Keywords: 
forces, friction, marbles, fair testing
Description of task: 
Task: students investigate the rolling distance of marbles on different surfaces. Assessment focus: processing information to answer a question.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Gather and interpret data
This resource provides opportunities to discuss fair testing in investigations and the patterns in the data collected. 
 
Capability: Use evidence
This resource provides opportunities to discuss the data/evidence required to support an explanation. 
 
An example of how this resource could be adapted to highlight the science capability Gather and interpret data  is available at TKI.

 

Science capabilities: 
Gather and interpret data, Use evidence
Making Better Sense: 
Friction
Answers/responses: 
a) Any 1 of:

  • One cluster of dots is further away.
  • All (or most) of the dots on the smooth floor are further from the bottom of the ramp than those on the carpet.
  • All (or most) of the dots on the carpet are closer to the bottom of the ramp than those on the smooth floor.
  • The blue dots are further from the bottom of the ramp than the red dots.
  • The red dots are closer to the bottom of the ramp than the blue dots.
b) smooth 
c) The carpet has more bumps on it, which slows the marble down.
or
Any answer that shows an understanding that there are more frictional forces acting on a marble on a rough surface than on a smooth surface.
NOTE: It is not necessary for students to use the term friction or force.
d) To make sure the result is a typical one.
[Accept similar answers.]
Diagnostic and formative information: 

For question c), some students discussed the characteristics of the surfaces, but not how this acts to slow the marble.  "The carpet's thick and the other one was smooth." Prompt them to start thinking about friction, asking them how the surface affects the rolling of the marble.

Teaching and learning

  • During our trials we noticed that students tended not to worry if the items they rolled hit the wall, as they were quite sure they knew which one was going to roll further anyway. Teachers can draw students' attention to principles of fair testing by asking questions that help students focus on whether aspects of the test are fair.
    Is it fair if the marble hits the wall?
    What could you do to stop it hitting the wall?
    [Look for answers such as "lower the slope of the ramps" or "move the ramps further from the wall". Check that they consider both ramps.]
  • We also noticed that it was common for students to focus on which marble went further rather than looking at the cluster of marbles, and what this tells them. Questions that help raise awareness that you don't get a single perfect measurement are:
    Does the same marble always roll the same distance? Why/why not?
    Which cluster of dots is further away from the ramp?

Some students may be capable of taking the comparison further. Taking eleven measurements makes it easier for students to identify the median for each group, and use that to compare the results.

Research
Young children cannot hold a lot of information in their heads at a time. Simplifying measuring so students can see the comparisons may allow them to more easily recognise the patterns that eventuate. The strategy of using coloured dots may also help them see the relevance of repeating tests (Hipkins and Kenneally, 2003).

Further reading about this research

  • Ministry of Education (2003). NEMP probe study findings 2003. Dunedin: Educational Assessment Research Unit. Developing children's science investigation skills, page 14, provides a clear teacher-friendly summary of a research project by Rose Hipkins and Natasha Kenneally about children's science investigation skills.
  • Hipkins, R. and Kenneally, N. (2003). Using NEMP to inform the teaching of science skills. Wellington: New Zealand Council for Educational Research.
  • Hipkins, R. and Kenneally, N. (2003). Simple teaching strategies to use during primary science investigations. Paper presented at ASERA Conference, Melbourne, July 8-12, 2003.
Next steps: 

Rolling marbles

  • Rolling marbles, which assesses planning a fair test in this context, could be used before students do this task.
  • Rolling marbles III, a similar resource at Level 2, is suitable for those Level 3 students having difficulty with managing all the variables.
  • Ministry of Education (2003). Marbles. Building Science Concepts, Book 42. Wellington: Learning Media.
  • Ministry of Education (1999). Making better sense of the physical world. Wellington: Learning Media. In the section on forces and motion, activities 10-12, pages 118-119, explore friction.