Working Scientifically Activity 3 – Designing an Experiment

Designing an Experiment - The Growth of Bacteria [Stage 4]

 * Main Focus: 1. WS5.2 Students plan first-hand investigations by:
 * a. collaboratively and individually planning a range of investigation types, including fieldwork, experiments, surveys and research
 * b. outlining a logical procedure for undertaking a range of investigations to collect valid firsthand data, including fair tests
 * c. identifying in fair tests, variables to be controlled (held constant), measured and changed
 * d. describing safety and ethical guidelines to be addressed
 * Other outcomes and content statements:
 * LW4 Scientific knowledge changes as new evidence becomes available, and some scientific discoveries have significantly changed people's understanding of the world.
 * a. research an example of how changes in scientific knowledge have contributed to finding a solution to a human health issue

Activity Outline
In this lesson, students will design an experiment in order to see how hygiene and antibacterial products can improve the reduction of disease.

At the start of the lesson, the teacher will lead the class in explaining the developmental history of sterile surgery and aseptic technique. Students will learn that before the 19th century, surgery often led to dangerous complications, serious disease or even death. They will assess the contributions of Louis Pasteur to biology and how his findings have changed the fields of medicine, science, agriculture and hospitality.

The lesson will be followed by an open-ended discussion of how students think that modern developed society prevent disease and infection in areas such as pre-schools, hospitals, restaurants, laboratories and toilets. The teacher will lead the discussion into the importance of washing hands regularly in daily life

For the main part of the lesson, students will be allocated into groups of 3-4. In these groups they will be given a list of materials they can use to carry out an experiment next lesson. These materials will include: Using these materials, students must design a first-hand investigation to test the given aim: ‘How do different materials affect the growth of micro-organisms found naturally on our hands’.
 * Agar plates
 * Hand sanitizer
 * Soap
 * Dirt/soil from outside
 * Tap water

Students will be informed that on the day of the experiment, the class will have access to an incubator. Using the online form provided (see link ), students will collaborate to create a hypothesis, identify their variables, design a method, and perform a safety evaluation. Students are encouraged to be creative with their design and not just simply ‘see what the others are doing’.

The forms will be submitted online, where they will be able to be accessed by the teacher.

Differentiation and considerations

 * Designing an experiment can prove to be a difficult and daunting task for stage 4 students, even the most gifted and excelled students. The teacher should assign groups that create diversity amongst each individual. Ensure that:
 * Friendship groups are separated to allow a wider peer engagement
 * Academic abilities are distributed evenly. All students have something to learn from someone at a different academic level to them (wether it be higher or lower).
 * Confident students and introverted students are distributed evenly
 * Due to this experimental design involving microbes and incubation, the dangers of contamination and infection must be stressed to all students. Ensure that students put a big emphasis on contamination and infection in their safety evaluation. If the safety evaluation is not adequate request the students to improve it.