Unit 1 Introducing Science

Topic

What factors affect melting of ice?

Curriculum Link

1 Introducing Science (Using common laboratory equipment to conduct a simple scientific investigation)

Estimated Lesson Time

80 minutes

Introduction

Experiment is essential to the learning of science as the results help us understand the relationships among different physical quantities. In order to properly carry out an experiment to yield useful results, variables have to be used to represent different physical quantities and values. These variables, according to their usage, are classified as independent variables, dependent variables and control variables.

To start with, students should be able to distinguish between independent variables and dependent variables. Viewing the following video clips may help students to have an idea about variables.

An animation of a teacher explaining variables about an experiment of plant growth:
https://www.youtube.com/watch?v=nzfDvfoBv_g

Another video clip on the concepts of variables about an experiment of plant growth:
https://www.youtube.com/watch?v=tK2mBsSb3uw

A video clip on the concepts of variables and graph plotting:
https://www.youtube.com/watch?v=tbGTfZ7gVsE

Teacher can show a video clip (https://www.youtube.com/watch?v=iXRcuR5A6ck) to show that ice on road can melt at a temperature lower than its melting point. Teacher then raises the question whether impurities affect physical properties of water, such as melting point.

Key Question

Will impurities in water/ice affect its physical properties, such as melting point?

Learning Objectives

In this activity, the students should be able to

  1. choose and properly use the suitable apparatus for an investigation;
  2. use appropriate units in the measurement of physical quantities;
  3. acquire skills in transferring solution, mixing solution, measuring weight, time, temperature and volume (SP1) and (SP4).
  4. acquire planning and designing skills (SP3) in designing and preparing the investigation, such as identifying independent and dependent variables;
  5. acquire comparing and classifying skills (SP2) by comparing results obtained with different control variables;
  6. acquire interpreting data skills (SP5) in analyzing the data collected.

Teaching Plan

Task (Time) Brief Description Materials Objectives

Engagement
(15 min)
  • Teacher shows different video clips to introduce and discuss the concepts of independent and dependent variables
  • Teacher then shows an everyday life example (salt is useful to melt ice on an icy road) and discusses with students whether impurities affect physical properties of water; and informs students to carry out an experiment for investigation in this regard
  • Teacher shows different apparatus and briefs students proper uses of the apparatus
  • Students plan how to prepare solutions with impurities in a sensible and systematic way

Different apparatus to be used in the investigation

(1), (2) & (4)

Exploration
(25 min)

PART (A) of the investigation

  • Students select and use apparatus to prepare the solutions and then put them into the refrigerator to freeze the solutions into ice cubes.
 (1) & (3)

Exploration
(30 min)

PART (B) of the investigation (another lesson)

  • Students measure temperature and time when ice cubes are melting and record the results
 (1) & (3)

Explanation
(10 min)
  • Students analyse and compare the data  obtained from different solutions and report any significant observations
 (5) & (6)

Exploration
(30 min)

PART (C) of the investigation (another lesson)

  • Repeat PART (A) for a particular solution, but with different concentrations
  • Students measure the temperature and time when ice cubes are melting and record the results
 (3) & (4)

Elaboration &
Explanation
(10 min)
  • Students analyse and compare the data of the same solution of different concentrations and report any significant observations
  • Students predict the values of dependent variables of other solutions in a similar/an identical investigation
 (5) & (6)