Falling play dough

Falling play dough

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about acceleration and fair testing.
You will be investigating how much equal sized balls of play dough squash when dropped from the heights shown (0.5m, 1m, and 2m)
  1. Before you begin your investigation, complete parts a) and b). 
  2. Plan and carry out your investigation to test your prediction. 
  3. Complete part c).

Question

diagram of 3 objects from different height
a)  Predict which ball will squash most when it hits the floor. Select your choice.

    • 1

    • 2

    • 3

    • All will be squashed equally

b) Explain why you think the answer you chose is correct.

Question 1Change answer

Plan and carry out your investigation to test your prediction.
 
Show your results here.

Question 1Change answer

c) Explain how your investigation gave you evidence for or against your prediction.

Question 1Change answer

Self-assessment sheet: Carrying out a fair test
Name:
Date:
My investigation question is: 
  1. I kept the size of the balls the same. YesNo
  2. I kept the shape of the balls the same. YesNo
  3. I carefully measured the distances. YesNo
  4. I recorded my results in a way that showed the information clearly. YesNo
  5. I planned how I would judge how squashed the balls were. YesNo
  6. I repeated the investigation to check that I got similar results. YesNo
  7. I used what I found out to think about the answer to the question. YesNo
 
One thing I need to improve next time I carry out a fair test is: 
Task administration: 
This task can be completed with equipment and pencil and paper or online.
 
Equipment:
Play dough; 3 metre ruler

NOTE:Commercial play dough bounces rather than squashes. Play dough made from the recipe below is suitable.
  • Ask students to talk about their prediction before they investigate. Some students will change their prediction, because they are afraid of being wrong. Encourage them to talk about gathering evidence for and against their prediction.
  • The trial students worked in pairs for the entire activity, which was followed by a whole-class discussion.
  • If you want a purely conceptual focus, the investigation could be replaced by a demonstration.
NOTE: It can be demotivating to always get students to plan their investigations in writing. The trial students successfully carried out this investigation by just talking about what they would do. A self-assessment sheet is included for students to evaluate their investigation, to help them think about whether the information that they gathered was valid.
 
Recipe for play dough
Mix together in a saucepan:
  •  2 cups flour
  • 1 cup salt
  • 2 teaspoons cream of tartar.
Add 2 cups of water and stir well. Mix in 2 tablespoons of oil. Heat over low heat, stirring occasionally, until thickened. Cool. Knead, and add colouring if desired. Store in a plastic bag in the fridge.
Level:
4
Curriculum info: 
Science, Investigating in science, Physical World
Keywords: 
physical inquiry, forces, acceleration, fair testing, self assessment, experiments
Description of task: 
Task: Predict which of three balls dropped from different heights will squash most, explain why, and design an investigation to test prediction. Assessment focus: acceleration and fair testing.
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 methodology of investigations and what makes them a fair test.
 
Capability: Use evidence
This resource provides opportunities to discuss different ways that students measured how squashed the balls and how this is evidence. 
Science capabilities: 
Gather and interpret data, Use evidence
Making Better Sense: 
Kinetic Energy
Answers/responses: 

a)

C ball 3 (2m fall)

b)

 Ball 3 has most time to accelerate/speed up and so hits the floor with greatest speed/force orball 3 is higher so it is going faster.
or
Ball 3 because it is higher / ball 3 because it is going faster.

c)

Student compares their observations to their prediction and makes a statement about the relationship.

This resource was trialled with 8 year 8 students, 4 boys and 4 girls, in November 2004.

Diagnostic and formative information: 

For question b) some students gave a partial explanation:

  • because it is higher up. Encourage students to further explain their ideas about how height affects the result, so they are including the relationship between height and speed.
  • because there is more pressure. (This is not the same thing as force. The force that is mostly acting on the play dough is the pull of gravity.) The word "pressure" suggests that these students need more scientific language to discuss their ideas. The teacher modelling the use of words such as "force" encourages students to include them in their own discussions.
When planning their fair tests, the trial students carefully weighed the play dough, but were less careful about the shape of the ball. Students could evaluate whether it is a fair judgement if the balls already have flat spots. All used flatness to judge which ball squashed most, but made no attempt to measure this in any way. Encourage students to think of ways to more effectively judge which is most squashed. The students in the trial were most likely to identify that repeating the investigation was the area they needed to improve on.

Research
Research (e.g., Project for Enhancing Effective Learning - PEEL) has shown that asking students to commit to a prediction in writing:

  • motivates them to want to find the answer;
  • can lead to animated class discussions as students justify their predictions; and
  • gives the teacher information about what the student is thinking, especially if they explain their reasoning