Which liquid flows best?

Which liquid flows best?

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Further Resources
Design a "fair test" to show which of the liquids you have been given flows the best when it  slides down a metal tray.
 
a) Write a plan for your "fair test" here. When you have written your plan give it to your teacher to check.

 
 
 
 
 
 
 
 
 
 
 
 

Plan checked by teacher? 
b) Carry out your "fair test". Record your results and observations here.

 
 
 
 
 
 
 
 
 
 
 
c) Write a conclusion for your "fair test".

 
 
 
 
 
 
 
 
 
 
Task administration: 
This task can be completed with pencil and paper and other equipment.
 
Equipment:
Cooking oil; golden syrup; detergent; 3 eye droppers; ruler; stop-watch; metal tray, e.g., the flat metal tray from the oven, or another object to run liquid down; books or other objects to prop tray up against.
  • This task can be done in groups of 2 to 4.
  • Give the students the materials listed above.
  • Instruct the students to design a "fair test" to find out which of the 3 liquids will flow the best. Students will need to define their ideas about what is "best".
  • You will need to check and amend students' plans before they carry out the "fair test" to ensure that the plans are feasible (see marking schedule).
Level:
4
Curriculum info: 
Science, Investigating in science, Material World
Keywords: 
properties, liquids, viscosity, fair testing, practical
Description of task: 
This practical task requires students to first plan how they could find out which liquid flows the best. Then they carry out their plan, record their results, and write a conclusion.
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 use investigatory practices to design, carry out and interpret results of a valid test.
Answers/responses: 
a) Designs or carries out a fair test which includes any 3 of the following:

  • "Best" flow is defined by the time taken to travel a given distance or the distance travelled in a given time, or a total distance travelled.
  • A set number of drops is used for each liquid/or x mLs from the eyedropper.
  • The starting point for all liquids is the same.
  • Slope of the tray is the same for all liquids.
  • Mentions or uses repeat trials.
b) For accurate recording of distance or time for all 3 liquids.
c) Accurate conclusion drawn from results, e.g., the cooking oil flowed best.

Possible extension questions:

  • Q:What is meant by the viscosity of liquids?
    A: viscosity is a fluid's resistance to flow, this is shown by all liquids.
  • Q: Name a liquid which has a low viscosity.
    A: mobile liquids such as water.
  • Q: Name a liquid with a high viscosity.
    A: e.g., treacle, oil.
  • Q: Lavas which are high in silica are viscous and sticky. What shape would the volcano made of this type of lava be?
    A: steep-sided, conical volcano, e.g., Taranaki. (Whereas volcanoes made from lavas low in silica are not as viscous and can flow for long distances, these form broad flat volcanoes, e.g., Rangitoto.)