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Learning News Week 2 Term 4

fig.5 Crash landing Rosetta onto a tiny comet.

Explosions in Science

Chemistry in Science classes invariably invokes a student to comment: “Let’s blow something up.” It is the perception that this is the main highlight of Chemistry and if our classes do enough explosions then Science will be a great subject and the teacher will be a great entertainer.

Fig1. Car engine.

Chemistry explosions happen all the time in students’ lives yet they generally ignore them. Every car engine [fig.1] explodes fuel in a careful sequence in beautifully machined cylinders. Aircraft fly across Brisbane skies powered by Rolls Royce jet engines that explode fuel in a spectacular way.

Explosions in Science can be successfully demonstrated as long as the products of the explosion are not trapped in a container. Hot gases have impressive force.

Fig.2 Methane gas bubbles.

Methane gas bubbles [fig.2] can be held in one’s hand and if lit will explode quietly with most of the heat going upwards with the exhaust gases. The photograph below illustrates the method. [fig.3] Now would a teacher allow a “let’s blow something up” student the opportunity to use his hand to hold the bubbles? Would the student’s parent think that this is “hands on” science gone too far?

Fig.3 Methane gas bubbles exploding.

Perceptions are a constant challenge for schools. Students walk into classes with perceptions of life and science firmly planted in the minds by outside sources; probably outside the school view, perhaps outside the family view.
Even the various definitions of perception suggest strongly of this. The second definition of “perception” in Wikipedia says “the way in which something is regarded, understood, or interpreted. For example, “Hollywood’s perception of the tastes of the American public”.

Year 6 and Year 8 are tackling the topic of Chemistry this term. The Year 6 classes will attempt not an “explosion” experiment but a multi-step experiment involving copper changing forms five times before returning back to its original state. The aim is to change the perception of our students. We want them to understand that chemical reactions change the arrangement of the atoms in a material often in a series of steps.

The students might spend 50 minutes following this experiment and return the next lesson to complete the last two stages. At the end of this time though we will be encouraging our students to write Beta sentences to explain what they saw in enough detail to show their understanding. A Beta sentence requires considerable effort to write, as the oral understanding needs to be logically connected. An alpha sentence might read, “The flask got hot and made disgusting smoke.” A Beta sentence might read, “the concentrated nitric acid attacked the copper wire vigorously, changing the copper into a green watery form while clouds of nitrogen dioxide filled the air.” [fig.4]

Fig.4 Copper changing forms.

The perception of class Chemistry changes here from fiery entertainment to a thorough understanding of an important reaction, carefully written out. Science will not be given significance by the general media. It will be the perception of the media that Science is a side issue in life’s understanding and enjoyment. We will be flooded by the upcoming excitement of the secret judge in this week’s amazingly talented X factor show, rather than be challenged to pause for five minutes and to wonder in awe of the achievement of crash landing Rosetta onto a tiny comet 700 million kilometres away from earth. [fig.5]

For students at ATC, we believe that by offering the best perception of a topic we are offering our students the opportunity to lift themselves out of the common media domain of superficial moments of entertainment. In this case, Chemistry in our Science classes is discussed as a great vehicle to help students think at a higher level and to write to show they understand concepts. Beta sentences are for Year 4’s as much as our Year 9’s. “Hands on” is only a minor part in the process.

What we do believe is this: It’s not about what our students are born with. It’s about how consistently and deliberately we can work together to improve their performance.

Greg Quinn, Assistant Dean of Learning