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May 2019

The Importance of Study Groups

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Study groups, everyone’s heard of them and everyone knows how important they are. But what exactly are its benefits and how can we utilise study groups most effectively? There is often a culture especially in the selective school bubble where students are reluctant to share notes and cooperate for the sake of competition, instead favouring to work alone. However, whilst that may work for some students, for many of us, it is much more beneficial to work in groups. Study groups contradict that culture, encouraging teaching and questioning in small groups. 

 

Benefits

One of the main benefits is the support and encouragements that study groups can provide. For many of you, year 11 and year 12 would be one of the hardest and most stressful years of your schooling career academic wise. A lot of that stress can come from the sheer amount of work that needs to be done. 

A study group can become a good support network. Getting support from those who are in a similar boat can alleviate some stress. Moreover, struggling students can ask questions in a less formal environment whereas ‘teachers’ also consolidate their knowledge. 

Different perspectives are of paramount importance when tackling difficult questions. These different perspectives can come in handy whenever someone is confused about a particular concept and when dealing with long response questions such as:

Evaluate the significance of the visible emission spectrum of hydrogen to the development of the Rutherford-Bohr model of the atom? (4 marks) (ACE, Light and the Atom Week 7).

Often, these questions have a very specific marking criteria and it can be quite hard to obtain all the possible marks. However, with the help of several people in your study group, those questions can be broken down and approached from different angles.

 

Tips for Effective Study Groups

A study group will be most effective if there is a schedule. Don’t say to ‘meet once every week’. Rather plan out which times everyone is free and make sure to go to a quiet place where everyone can discuss and focus. An empty classroom is always a good bet if you want to stay at school especially during times like lunch times. Remember to take breaks and not to go too late into the night so that everyone is still refreshed. 

Stay organised for the study sessions. Your study groups will only be as effective as the amount of effort everyone puts in. Be prepared for each session and remember to bring the essentials such as the syllabus and any relevant textbooks. Encourage everyone to be active and ask questions as difficult concepts can often be consolidated when you teach someone else. The ACE booklets provide a wealth of knowledge and there are many questions and concepts that can be discussed in a group for in the theory, PBC and tutorial sections.  

Finally, a study group is there for everyone to work towards a common goal. Treat everyone with respect and come to the sessions eager to learn. Good luck!

BY LOUISE CAI

Scientific Discussions 101

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Depth Studies: Writing a Discussion

The implementation of the depth study to the science syllabi is a change that has left a lot of students uneasy. After the hurdle of, in most cases, having to choose a depth study focus and carry out first hand investigations, students are prompted to engage in evaluations of their scientific procedure and suggest ways that future experimentation could be improved. As arguably one of the most difficult and crucial aspects of the depth study, we are here to breakdown the key elements of a successful discussion.

Before we can begin this process of evaluation, it is important that we understand the core differences between discussions of accuracy, reliability and validity, as it is not uncommon for students to use them interchangeably. 

 

Reliability

Definition:

Reliability is concerned with the consistency of your results, that is, the degree to which each of the results deviates from the next. As such, reliability can only be determined if the experiment is repeated at least three times, for each change of the independent variable. If we sketch our data points, the scatter or deviation of points from the line of best fit, is also an indication of the reliability. If multiple outliers are present, we can deduce the experiment is not reliable.

What affects it:

Random errors are responsible for limiting the reliability of our experiments. Random errors are characterised by their varying magnitude on our experimental results as they are equally likely to be above or below the mean value. The degree to which they have altered our values above or below the expected is often difficult to determine. 

How to assess:

One of the first means of identifying sources of random error is to reflect on the errors which have come about due to reliance on humans. Two common examples include human reaction time when using a stopwatch, approximately 0.2s, and the application of a force when releasing objects. Other sources of random error may be sudden temperature variations or fluctuations in ambient light in the school lab.

How to improve:

Whilst it is correct to say that repetition plays an important part in determining whether an experiment is reliable, repetition does not work to increase reliability. Instead, to increase the reliability of our experiment we must reduce the effect of random errors. The easiest way to minimise random errors is to increase the number of measurements we take within the data range, for example rather than measuring at 0, 20, 40, measuring at 0, 10, 20, 30, 40 or, increasing the readings over a larger data range. We can then consider reducing the potential for human errors by implementing different technologies. For example, instead of using a stopwatch to determine the time taken for an object to travel a set distance, a video camera can be set up to record the object’s motion or a set of light gates could be used.

 

Accuracy

Definition:

Accuracy is a quantitative measure of the extent to which our experimental results deviate from the expected or published values. The most successful way of deducing the accuracy of an experiment is by calculating the percentage error,

% Error= (|Experimental Value – Expected Value| ÷ Expected Value) × 100%

It is often quoted that a percentage error below 5% renders the experiment accurate, however, depending on the quality of the equipment involved, an error of up to 10% can still be considered accurate. Be sure to define your percentage error tolerance when you make this judgement.

What affects it:

Systematic errors are responsible for limiting the accuracy of our results, and are often much more difficult to detect and hence harder to eliminate. Different to random errors, systematic errors alter our experimental results by a fixed, constant value each time we conduct the experiment.

How to assess:

For systematic errors, we often look at the equipment we used in our investigation. For example, a wooden ruler used to measure distances may introduce systematic errors since the zero increment may have faded and caused every measurement to be out by 1mm or the ruler itself may have shrunk or expanded into an irregular shape overtime by virtue of the wooden material and temperature changes in the environment. Other common systematic errors include; forgetting to tare an electronic balance, not zeroing the stopwatch, and not aligning our eyes with the increment markings we are reading, which results in parallax errors.

How to improve:

In order to improve the accuracy of our experiment, we want to replace existing equipment with equipment that is typically able to report to more significant figures, less susceptible to changing composition over time and which minimises the need for human interpretations. We must ensure that all measurements are taken with our eyes at level with the device to eliminate parallax errors and calibrate or zero all digital equipment before use. As examples, we could consider replacing the electronic balance with one that measures to 6 significant figures rather than just 4. Or, we could replace our generic thermometer with a digital one.

 

Validity

Definition:

Validity is a measure of how successfully our method addresses the aim of the experiment, unlike accuracy and reliability which are concerned with the outcome or results of the experiment. A simple way of determining validity is to consider the various assumptions that have been made whilst you have conducted the experiment, whether these assumptions are necessarily true, and whether they may have impacted the data obtained. Validity also relies on the experiment having strictly one independent variable – the variable being changed, one dependent variable – the variable being measured, and all other variables controlled. Importantly, there is no spectrum of validity and as such you must make a definite judgement as to whether an experiment is valid or not.

How to assess:

A good starting point for assessing validity is to consider whether any physics principles or equations have been used to interpret the data. In the simple pendulum experiment, we relate the length of the pendulum string, L, to the time taken for the pendulum to complete one swing, T, using the equation:

                                                           T=2πLg 

This equation relies on the assumption that the pendulum undergoes strict harmonic motion and not conical pendulum motion. A related assumption is that the angle of deviation when first setting the pendulum into motion does not exceed 7-10o. A further assumption we make is that the string used is massless and inextensible. The validity of our experiment would be compromised if any of these conditions were not met. Some more factors which may affect the experiment’s validity are the presence of air resistance or friction along a surface, as these factors are often assumed to be negligible in physics equations.

 

Summary

From what we can see, discussions of reliability, accuracy and validity in relation to scientific experiments can vary greatly depending on the nature of your investigation. It is important that when you construct these discussions, you do not rely on generic responses when evaluating. Instead, use the above definitions and examples as guidelines for your own thinking – the more specific your response, the better.

BY CHLOE BEYDOUN

Using the old syllabus to prepare for the new syllabus!

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There’s no past papers for our syllabus – is it still possible to do well? Everyone knows that the key to doing well is through practising with past questions.’

We’ve all heard about the new changes to the HSC Syllabus. But what exactly has been changed, and how do we reuse old resources to prepare for our exams?

Why the change, and how is the syllabus different? 

Imagine that instead of solving mathematical equations, we were tested on the history of Pi. Although this is nice to know, it isn’t crucial for pursuing mathematics in the future. Enter the NESA Board – they have removed lots of rote-learning of scientific history and ‘social context’, and replaced it instead with more concepts of ‘true science’. This is good news for students who struggle with simply memorising and rote-learning, since it puts a higher focus on understanding the actual scientific concept.

The new syllabus can be found on the NESA website below:

http://bit.ly/2Vvhfhr

It’s important to go through the syllabus dot-points to make sure you’ve covered everything that you need to know. Luckily, Ace structures it clearly for you by bolding the syllabus dot-points in the Theory section and going through each dot-point in detail, so you won’t miss out on any part in the syllabus.

Can we still use past papers?

The answer is yes. Although the syllabus has technically changed, this change is not as significant as you would think. Much of the content from the old syllabus is still recycled in the new one – you will find that when you are going through past papers, familiar questions will jump out at you. This is applicable for both Chemistry and Physics. A few are listed below:

 

Past HSC Question (Old Syllabus) New Syllabus Dot-Point
2004 HSC

Chemistry

Account for the cleaning action of anionic detergents.

(2 marks)

Investigate the structure and action of soaps and detergents

(Organic Chemistry)

2015 HSC

Chemistry

The graph shows the changes in pH during a titration.

Which pH range should an indicator have to be used in this titration?

(A) 3.1– 4.4

(B) 5.0 – 8.0

(C) 6.0 – 7.6

(D) 8.3 –10.0

 

Investigate titration curves and conductivity graphs to analyse data to indicate characteristic reaction profiles.

(Acid Base Reactions)

 

2010 HSC Physics

An astronaut on the Moon throws a stone from the top of a cliff. The stone hits the ground below 21.0 seconds later. The acceleration due to gravity on the moon is 1.6 ms–2. 150 m 300 m

a) Calculate the horizontal component of the stone’s initial velocity. Show your working. (1 mark)

(b) Calculate the vertical component of the stone’s initial velocity. Show your working. (2 marks)

(c) On the diagram, sketch the path that the stone would follow if the acceleration due to gravity was higher. The initial velocity is the same. (2 marks)

Solve problems, create models and make quantitative predictions by applying the equations of motion relationships for uniformly accelerated and constant rectilinear motion

(Advanced Mechanics)

2016 HSC Physics

In a thought experiment, a jet is travelling at 0.5 c relative to the ground, towards a train that is travelling at 0.1 c relative to the ground, as shown. What is the speed of the light emitted from the train’s headlight, as measured by a pilot in the jet?

(A) 0.1 c

(B) 0.4 c

(C) 0.6 c

(D) 1.0 c

Analyse and evaluate the evidence confirming or denying Einstein’s two postulates:

– the speed of light in a vacuum is an absolute constant

–  all inertial frames of reference are equivalent

(The Nature of Light)

So, whilst going through past papers, don’t stress too much if you see questions completely unrelated to what you’ve been learning. Instead, it would be more helpful to target your practice towards questions focused on a specific topic (as explained later). In terms of theory, there will be slight differences; however, there are certain broad topics that are carried over. In Chemistry, topics such as equilibrium, titration, ion testing and atomic absorption spectroscopy are carried over, albeit in more detail. For Physics, a large majority of the old syllabus remains, in particular: motion, electromagnetism, properties of light, quantum mechanics and nuclear physics. Both new syllabi, however, have a greater focus on application of knowledge. For Chemistry, this may look like more problem-solving based questions whereas in Physics many of the questions will be calculations.

How should I approach my study using a mixture of old and new syllabus resources?

We’ve compiled a list of different types of old and new resources which you can look at as the exam date comes closer.

  • Ace PBC and Tutorial Questions: These creative calculation and theory questions not only help you revise the weekly content but are also designed to inspire you to think outside the box when approaching exam questions. It is essential to complete Ace’s Tutorial questions during the week before your next lesson to further retain your knowledge. Also, the likely ‘mark allocation’ given for each question is extremely useful in giving you an idea of what and how much to include, and how to structure your responses – particularly in an exam setting with time constraints.
  • Past HSC Questions: Not all previous HSC questions will be relevant, but it is still good to have a skim through these old papers and attempt any questions targeting common topics. In particular, calculation questions from both subjects will be relevant as these have not changed from the old syllabus. Make sure to look at the marking guidelines as this provides a valuable indication of where NESA likes to allocate its marks.
  • Past Paper Questions:  Past papers from other schools can be found online through a number of website resources, such as: https://thsconline.github.io/s/. Here, it’s important to selectively choose the questions relevant to your study.
  • Textbook Chapter Reviews: For extra information, textbook chapter reviews will also contain extra questions, including those from the new syllabus.
BY JOYCE WU