Unit 1 Introducing Science

Topic

Extraction of orange juice

Curriculum Link

1.3 Using common laboratory equipment: proper use of measuring instruments
1.4 Conducting a simple scientific investigation: fair test

Estimated Lesson Time

80 minutes

Introduction

In this activity, students will tackle a daily life problem with the concepts of fair test. They are required to design and conduct a simple investigation to figure out which method can extract more juice. Teacher is recommended to guide students to define 'amount of juice' in terms of volume and use a single orange to study the two methods instead of two oranges since using two oranges induces greater error as they may contain different volume of juice initially. In a context of problem-base learning, students will learn the proper use of measuring instrument.

Key question

Which method can extract more orange juice?

Learning Objectives

In this activity, the students should be able to

  1. identify appropriate parameters to represent the data being compared;
  2. design and conduct an experiment to compare which method can extract more juice (SP3);
  3. properly use different measuring instruments of volume for the study (SP4);
  4. analyse and interpret data to draw a conclusion (SP5);
  5. plan an alternative method for achieving the same objective (SP3).

Teaching Plan

Task (Time) Brief Description Materials Objectives

Engagement
(5 min)
  • Teacher engages the class by introducing the scenario and asking students to justify which method can extract more juice.
  

Exploration & Explanation
(30 min)
  • Students explore the parameters which can be used to represent the 'amount of juice'.
  • Teacher guide students to explain that using two oranges (one orange for each method in the test) is problematic because each orange may originally contain different volume of juice.
  • Since it is hard to ensure two oranges contains same volume of juices, it is recommended one large orange can be used and first cut it into two equal halves for the two methods:
    • Method 1: cut one half into two equal slices
    • Method 2: cut one half into three or more equal slices
  • Teacher asks students to describe how different measuring instruments can be used.
  • Teachers can discuss the advantage and limitation of different instruments (different beakers and measuring cylinders).
 (1) & (2)

Exploration & Evaluation
(30 min)
  • Students explore the better method through conducting the practical.
  • Students analyse and interpret data as well as draw a conclusion.
  • Teacher guides students to explain different data collected among the groups.
 (3) & (4)

Elaboration
(15 min)
  • Teacher guides students to elaborate an alternative to represent 'the amount of juice' - measuring the percentage change in mass of orange.
  • If time is allowed, another lesson can be arranged for measuring the change in mass (the change in mass of orange as the dependent variable instead of the volume of juice).
 (5)

*Apparatus and materials required: