Practical skills and Maths skills for A-Level Chemistry and Biology

Practicals maths a-level chemistry and biology

This is part 5 of a 6 part series which will teach you how to study for A-Level Chemistry and Biology.

In part 4, we talked about developing good study habits to help you successfully learn the content. A-level Chemistry and Biology aren’t just about learning the subject though, they’re also about learning how to actually do science. This involves learning a whole new set of practical skills and the maths skills that go with it. This is what we’ll cover in part 5:

 

1.Make sure you learn the practical methods

 

For both Chemistry and Biology you have to perform a number of core practicals as part of your studies. The exams will contain questions that relate to these practicals.

Unfortunately, you won’t learn the skills you need to answer the exam questions just by doing the practicals. This means you need to make time to study the practicals themselves.

This will be easier if you get a text book that covers practical Chemistry/Biology. Ideally, get one that’s meant for your exam board. The Hodder A Level text books for AQA are reasonably good for the practicals and the Pearson text books for OCR are a good option.

The lab book you complete at school will also be helpful but you’re unlikely to be able to take it home until just before the A Level exams. If this is the case, ask your teacher if you can take pictures of the work you’ve done in it so you can look back over what you’ve done. Make sure you understand every step of the method and if you’re not sure why you did something, ask your teacher.

Remember, in the exam they are likely to as you to suggest a method for a practical procedure. Make sure you’re ready for this. Practice writing out a method for each of the core practicals. The examiner will be looking for more detail than you’d think, so try and avoid over-summarising.

As well as studying the practicals, you need to learn about the ‘scientific method’, as this dictates how we design experiments.

Make sure you understand the meaning of terms such as“accuracy’, ‘reliability’ and precision mean in the context of science. It’s very important to bear these in mind when you’re writing a method. You should also practice evaluating and suggesting improvements to methods.

And practice drawing graphs, especially working out an appropriate scale. Most students seem to lack confidence with this but it get’s easier the more you do it.

You’ll find plenty of practical questions in the old specification practical unit papers. Despite the different form of assessment, these questions will still help you develop your skills. Your teacher should be able to point you in the direction of these.

 

2. Be honest with yourself about your maths skills

 

You don’t have to be doing A-Level maths to cope well with the calculations. But you do need to be ready to fill in the gaps in your maths knowledge that are holding you back

The Biology exam is 10% maths and the Chemistry exam is 20% Maths so you can’t hide from it.

As we mentioned earlier, the specification tells you what you need to know. Plus, as you do past papers you’ll see how this fits in with the science content.

If you see something on there that you know you’re weak on, deal with it. Dig out your old GCSE books or watch some youtube videos. Ask your friends who are studying maths to help you.

As a starting point, one thing I find most students struggle with is ratios. They come up a lot in Biology, so this is definitely something for you to make sure you’re confident with.a

Even if you are studying A Level maths you’re still likely to struggle with the calculations to some extent. This is especially the case for Chemistry. From a mathematical point of view, the calculations are very simple. differently in science to what you’re used to in maths. The way we treat rounding and significant figures is a good example of this, so you need to learn what’s expected.

Overall, the maths requirement is a particular area where you need to make sure you avoid the illusion of competence we talked about earlier.

 

3. Make a special effort to practice unit conversions

 

This might sound random, but unit conversions are so important and cause so much trouble that they need a tip of their own.

Whenever you learn a particular calculation, you need to make sure the correct units associated with all the variables.

Be aware that the same variable may use different units in different sciences – this is an issue more with Chemistry and Physics. You are often given variables with the ‘wrong’ units so you’ll have to convert them to the required units.

This sounds simple enough, and it is. Except your brain will make you do it wrong more than you realise.

Let’s try an example.

 

HOW WOULD YOU CONVERT GRAMS TO KILOGRAMS?

 

For many people (including me) the brain’s immediate response is to go “well, kilograms is the larger unit so I need to multiply”.

Except that’s not the correct logic. The correct logic is that kilograms is the larger unit so you’ll have fewer kilograms than grams. This means that you need to divide.

E.g. if you want to convert 50 g to kg then 50 / 1000 = 0.05 kg.

You may be sitting here now thinking “That’s ridiculous, no one would do that wrong”. But I GUARANTEE you will get your conversions wrong at some point, especially when you’re nervous in the exam. To reduce the risk of this, you need to get a proper thought process in place.

This is the thought process I use to help me:

TO CONVERT A LARGER UNIT TO A SMALLER UNIT :

(For example to convert kg to g)

You need to multiply because you’ll have more of the smaller unit than the large unit (e.g. you’ll have more g than kg).

 

TO CONVERT A SMALLER UNIT TO A LARGER UNIT:

(For example to cover g to Kg)

You need to divide because you’ll have fewer of the larger unit than the larger unit (you’ll have fewer kg than g).

I always think of the relationship between centimetres and metres to remind me of this.

Imagine measuring a table. If the table was 110 cm long, you would instinctively know that the measurement would be ‘smaller’ in metres, i.e. 0.110 m. The other way round would be ridiculous – you’re not going to have a table that’s 11,000 metres long!

Thinking about this way seems to work for most people. If it doesn’t work for you, that’s fine. Just find a way of thinking that does help. You don’t want to be sitting in the exam thinking “Oh no, do I multiply or divide?!”.

 

 

In the final part of this series, I’ll give you some tips on how to make the revision process as painless as possible.