junior cert science

JC Science: Guide to Revising

A big problem with students who wish to do well in their exams is that they simply don’t know how much they have to know!

It’s a perfectly understandable complaint, and hopefully this will help.

Remember that for each chapter you will have to know:

  1. All definitions (see the notes I hand out in class)
  2. All experiments (whether mandatory or not)
  3. All maths problems (see separate guide to answering maths problems).
  4. Graph questions (see separate guide to answering graph questions).
  5. Any other theory

Get your friend/Mom/Dad/brother/sister to ask you the exam questions from the questions at the end of each chapter in my notes – all the solutions are there to check with.

When revising the Experiment questions don’t waste time writing them out fully. Sketch a quick diagram labelling all the main parts, and then write down one or two sentences summarising what you did.

You can go into more detail in the exam itself – this is just to check whether or not you can remember the experiment.

Get into the habit of marking/highlighting what you don’t understand, and then either ask a friend to explain it to you, or ask me.

Make sure you don’t leave it and hope that it won’t come up in the exam!

Most students who get A-grades in the Leaving Cert do this a lot. I don’t think it’s just a coincidence!

Try to revise one chapter of science per night.

BTW, this took time to put together so don’t be afraid to say thank you; you would be surprised how much a few small words could be appreciated (by all teachers, not just me!).

Good luck!

How to get an A in Junior Cert Science: Part 2 – the graphs

Since this science course was first examined in 2006 graph questions have become quite common.

There are different types of graph questions, and we will look at each of these different types in turn.

There is nothing scary here, and you have probably covered them all in maths anyway. It’s just that the science textbooks don’t seem to do a very good job of telling us why we have them in the first place, or why there are different types.

Why do we have graphs?

You won’t get asked this so you don’t have to learn it off by heart – I just thought you deserved to know.

There are many different reasons, but we’ll just look at two here.

Reason 1:

To see what the relationship is between two variables, e.g. between the extension of a string and the force which caused it.

Now assuming that a bigger force causes a bigger extension, the question is; are the two quantities directly proportional? i.e. if the size of the force doubles then the extension should be twice as much, if the force triples the extension will be three times as much etc.

Another way of saying this is that the two quantities increase at the same rate (as force is increased the extension increases at the same rate).

Or finally the scientific way of saying this is to say that the two quantities are directly proportional to each other (you must learn the phrase in italics off by heart because it gets asked a lot as you will see below).

To investigate this you would plot the results on a graph, and if the two quantities are directly proportional then you will find that if you draw a line through the points you will end up with a straight line through the origin (the origin is the (0,0) mark).

 

Reason 2:

In some graphs the slope of the line gives us some extra information (and you must know what this is).

There are only three graphs which fall into this category so make sure that you know each of them.

1. The slope of a distance-time graph corresponds to the speed (or velocity) of the moving object

2. The slope of a velocity-time graph corresponds to the acceleration  of the moving object

3. The slope of a voltage-current graph corresponds to the resistance of the resistor under investigation.

 

Note that for each of these graphs you will also get a straight line going through the origin, which verifies that the two quantities are directly proportional to each other.

 

Which brings us to our next problem – how do we calculate the slope of a line?

 

To calculate the slope of a line

Pick any two points (from the graph) and label one point (x1y1) and the second point (x2y2).

Make life easy for yourself by picking (0,0) as one of the points (assuming the line goes through the origin).

You must then use the formula:                                    

slope = (y2 – y1)/(x2 – x1)

Note that you can also find this formula on page 18 of the new log tables

Yo – Which axis is the y-axis?

Remember the yo-yo? It goes up and down right? Well so does the y axis (and it begins at zero) so y-zero = yo

Now that’s just freaky.

How to get an A in Junior Cert Science: Part 1 – the maths bits

Many students are turned off Physics because of the maths involved, yet you only need to be able to do ordinary level maths in order to answer all questions which will appear on the Junior Cert paper.

Some of these are in the new log-tables, but others are not so you should really try to remember all of them because it not always easy to identify the formula you need from the list in the log-tables. Practice looking for them in pages 51 – 56.

To encourage students not to give up on these questions I have put together a document which includes all the equations on the Junior Cert Science syllabus. There are (only) ten of them and by-in-large they are very straightforward. The document includes every maths question that was ever asked on a Higher Level or Ordinary Level paper from when the syllabus was first examined in 2006 up until 2010. It also contains solutions to all these questions.

If you’re looking for a top grade in June you really should ensure that you’re familiar with all of these.

You can download this document here.

There’s also a section on Units (we tend to be a little fanatical about these in Physics) and finally a list of practice questions.

If you’re using this as a teacher it should make a nice revision class or two – good luck with it!

Assessment in Junior Cert Science – what a shambles; what a cod!

Here’s how to get 35% of your Junior Cert Science mark without having to learn any Science:

  1. Get the first 10% by having your lab book written up – it’s automatic and doesn’t necessarily mean you did any experiments. It certainly doesn’t mean you learnt anything; in fact if you missed out on any expeiments just copy them from somebody else and make up a date (try to ensure it was a day when the school was open).
    Technically we the teachers shuldn’t be signing off on this section unless we know it represents a fair reflection of the students’ actual work, but in practice this is rarely going to be the case. it may be that we see the results our students get as a reflection of our own teaching ability; we may have inherited the students from other teachers or indeed schools so may have no way of knowing how much of the previous work is legitimate; it may be a task too many for already busy teachers to monitor, particulary if the students themselves have little regard for the excercise or simply lack the necessary organisational skills to keep up to date themselves.
  2. Get the next 25% by having your two designated investiagations written up in the correct format. This isn’t very difficult and the average mark here is about 90%. The important thing to remember here is that it doesn’t matter how well you did the actual investigations or how clever your approach was (or indeed if you bothered to do the investigations yourself in  the first place) – all the marks here go for how you write it up.

If you think the final mark that students actually obtain may be somewhat inflated by the hoop-jumping above, you’re not alone. In fact some of us would go so far as to think it makes a mockery of the whole subject at this level.

Energy – the most poorly-taught concept in all of science?

It is important to realize that in physics today, we have no knowledge what energy is.

Richard Feynman

Sometimes when I’m teaching I have been known to go off on a tangent which may be only marginally related to what we’re doing in class; other times I manage to restrain myself and may just allude to the tangential concept in passing.

But then there are times when these tangents are actually necessary, and by leaving them out I am doing the students an injustice. Ususally I try to include this information in the students’ notes also but sometimes I just don’t get around to it. Energy is just such an example.

Georgina (this is where I’m supposed to say that Georgina is not her real name, but as far as I’m aware it actually is) is one of the top students in my fifth year class this year and I used to think that she was a bit of a ‘slogger’ – liked to work hard and liked to know that there was always a ‘correct’ answer. In fact I wasn’t even sure if she would adapt to my style of teaching, where I tend to ask questions and not always provide the answers. But Georgina showed what she was really make of when we were revising the chapter on Energy.

“I know this sounds like a silly question”, she said, “and I know we’re finished the topic now, and it’s not that I can’t do the problems and exam questions because I can, it’s just that I don’t seem to get what energy actually is

I realised that there was more to this student than I first thought.

You see nobody gets energy; in fact by pretending that it’s all straightforward we actually do the students a disservice. Not only are we ignoring the wonder associatied with the idea, we are also denying them the opportunity to engage with the concept at any level beyond the superficial.

Bottom line – nobody gets energy because there’s nothing ‘to get’. Energy is not tangible (alghough it is ‘an indirectly observed quantity’ if you want to sound clever), you can’t hold it in your hand, you can’t weigh it on an electronic balance, you can’t see it, touch it, smell it etc. Yet when the universe was first created there was a certain amount of this put in to the mix (actually now that I think about it the mix itself was energy (with perhaps just a little dash of time)), and it’s all still there today. Its form can change, but the energy itself can’t ever disappear – no sirree bob.

It could be argued that it is in fact merely an accountant’s trick which enables him to ensure that all actions balance.

Consider the following analogy which I like to use.

If a child asks you ‘what is money?’ you could take a few coins out of your pocket and show them to the child and say ‘this in money’. Now fast forward a couple of decades; all transactions are now done electronically/online and all coins and paper money are no longer legal tender. Now how do you explain what money is?

Well it’s a means of payment for goods and services, right? Somebody sells you an orange and you agree to transfer into their account a set amount of this ‘money’. And now that the shopkeeper has this money in his account he can use it to buy something else. So it’s a bit like a transferrable IOU.

Now energy is a bit like this, but there is only a certain amount of IOU’s in the universe and this was set when the universe first came into being (I’m not sure if we know how much energy is in the universe – presumably we do?), although to complicate matters since the early part of the last century (thank you Albert) we now know that all matter (‘stuff’) is basically energy in another form.

Anyone still with me?

Now the point of all of this  is to highlight once again that there is no reference to this concept on either the Junior Cert or Leaving Cert syllabus. It could be argued that this is because it would be too difficult, but the obvious response to this is that nobody understands Energy as it is currently presented anyway. Students merely learn off the definitions and formulae and if they think about it at all will probably just assume that it’s just another example of Physics being ‘too hard’ to understand.

So what’s the actual point in asking students to learn the definition in the first place?

In fact I’d imagine many students who can give the appropriate definition for Energy (“Energy is a form of Work”) couldn’t follow up by explaining what Work is (it’s a mathematical product of force and displacement to give the simplified version).

At Junior Cert level students are expected to be able to show how light and sound are forms of energy – again most students should be able to give the correct demonstration but if you ask them how this demonstration verifies that it is is form of energy few will be able to give a convincing answer. In fact while Energy is the single greatest unifying concept in all of science, even that idea alone is not worthy of mention in the sylllabus; as a consequence Energy is seen as just another chapter to be learned off, with (once again) no emphasis on how it ties together everything else.

Now if teaching Junior Cert Science and coming from a Biology or Chemistry background what are the chances of your students developing an appreciation of this all-encompassing concept? – were you ever told about it?

I thought I’d find something on YouTube to illustrate this, but I couldn’t find anything.

What is it about this idea that we want to avoid?

Below are some quotes from other more prominent commentators on this elusive concept:

When Feynman wrote,

“It is important to realize that in physics today, we have no knowledge of what energy is,” he was recognizing that although we

have expressions for various forms of energy from (kinetic, heat, electrical, light, sound etc) we seem to have no idea of what the all-encompassing notion

of “energy” is.

The various forms of energy (½mv2, mgh, ½kx2, qV,mcT, ½I2, ½CV2, etc.) are abstractions not directly observable.

2007 American Association of Physics Teachers

Feynman’s quote in context:

 There is a fact, or if you wish, a law governing all natural phenomena that are known to date. There is no known exception to this law – it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call “energy,” that does not change in the manifold changes that nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says there is a numerical quantity which does not change when something happens. It is not a description of a mechanism, or anything concrete; it is a strange fact that when we calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same. It is important to realize that

in physics today, we have no knowledge of what energy “is.” We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. It is an abstract thing in that it does not tell us the mechanism or the reason for the various formulas.

The Feynman Lectures on Physics Vol I, p 4-1

Junior Cert Physics Investigation 2010/2011

The junior cert science investigations for 2011 were published recently and the phyiscs investigation is as folows:

Investigate the factors that determine the force of friction between a  wooden block and the surface on which it is resting.

As usual,  there are few spaces for science teachers to discuss how best to implement this investigation so for what it’s worth I’ve decided to throw out my thrupenny worth of ideas and resources.
Why should my students have an advantage over other students who perhaps have a biology specialist as their teacher? Hopefully a Biology/Chemistry teacher will reciprocate with their comments on the other investigations.

Alternatively maybe a student will happen upon this blog post as part of their research – if so good luck to you. Please let us know how you’re getting on and we will try to help.

Some points to consider:

  • You would imagine that the orientation of the block would make a difference: if the block is standing on edge then there is less surface-area and presumably less friction. But presumably isn’t good enough in physics; many (maybe even most) relationshiops in physics which were originally thought to be obvious turn out after suitable investigation to be actually wrong. Can you think of any?
    To see a demonstration of this see the link here (pull the tab at the bottom over to the 10 minute mark – thanks to colleague Dee Maguire for the link and the heads up on the approach above).

 

  • There is a another nice counterintuitive concept – if students  are playing with different types of sandpaper they may well find that  the friction force between the wooden block and the roughest type of sandpaper is actually less than the force of friction between the wooden block and the lab-bench.
    Hopefully the students will first notice this stange relationship and then figure out why for themselves (this should then form part of their report. Partial explanation – the grains in the very rough sandpaper are acutally acting like little ball-bearings (see link below for an animation).

 

  1. Friction between two rough surfaces from absorblearning.com
  2. Friction between two rough surfaces
  3. The effect of ball-bearings in reducing friction
  4. The effect of lubrication in reducing friction
  5. Rub the two books against each other and note the rise in temperature

BOARDS.IE – An intriguing resource

boards.ie

boards.ie seems to win awards every year for its site. For me it merely highlights the fact that everybody seems to be communicating with each other except teachers – sure what would we have to talk about?

Well here’s an interesting nugget – from the comments below (pasted from the relevant boards.ie pages) it would appear that quite a few teachers are not sure what they are supposed to do with their students’ experiment copies, or how to fill in the green investigation booklets. Remember that if the students don’t tick the relevant experiments in their green booklets then they automatically forfeit 10%.

The site itself is also a very useful resource for getting student feedback on their various exams – these kids tend to have more honesty and intelligence than we (I?) give them credit for:

ok everyone, don’t forget your hardbacks tomorrow!

What you mean “hardback”?

Experiment copy? I nearly forgot! Thanks guys for reminding me

Dunno what he is on about, you don’t get marked on your hardback. Maybe he means just for study purposes?

I’m not sure..

You get marked on your mandatory experiment hardback

Think he means your experiment copy?? I think!

Exactly. DO NOT forget it. If they go to check yours, and you’ve ticked the boxes to say you’ve done it, and its not there, they count that as cheating.

nah you’re not supposed to take it in with you afaik…the supervisors would have reminded us anyways….

They inspect a small % of schools and the hbacks are sposed to be with your science teacher.
You’re meant to bring it in because every year they check a few schools, and if they check your school and they’re not there for inspection you lose your 10%

We’ve been told a million times to bring ’em in tomorrow

Our teacher collected ours at the end of April, she said there was a deadline I had to do about 15 experiments in the space of 3 days!

But the inspectors only come in the summer!
I’ve had to write up a good few today, but that was my own lazy selfs fault..

ive a few only not filled the science teacher said it was ok since half the class or more didnt get em finished either =P

I aint bringing mine in that’d be effort and no one told us to we were given them back and told it was fine?

Gawd im confused i ticked no boxes =S my science teacher is crap we have been reading out of a book all year and havent done any experimanens execpt for the 2 ones you did for 25%

My science teacher told us that we put them in a little pocket in this folder that also has our investigations in it. They just check to see whether you’re telling the truth or not. sure if yer teacher told u its fine then its not yer fault so theyd probably give you the marks

Exam done in 43 minutes. All spaces filled. No blanks. Two questions I couldn’t answer (one on chromosomes, one on the Hoffman Voltameter). Everything else is as far as I know it, correct. Junior Cert science in need of reform? hell yes
I know I’m probably not alone on this front.

have to agree ! left at about 10:30, that exam was an insult to my intelligence

For the green lab books did we have to tick something or do we just do the experiments and hand it up?…..i already have it handed up but didnt tick anything..??

You didn’t tick anything if the project booklet to say you did the experiments. I’m sorry to say if you didn’t, that’s 10% gone, it happened in my school before