Logarithms

In last week’s post I talked about the work that we had completed on indices and how we were using this to launch logarithms and exponentials this week. The benefits of this approach were shown up during one of the indices lessons when one of the students was tackling the following question (taken from Stuart Price’s Problem Book, @sxpmaths):

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He asked if there was an easier way to tackle problems like this, suggesting that if the numbers were much bigger it would make the problem more difficult. This was a perfect opening for introducing logarithms, which we did with a series of similar questions.

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When planning this lesson in discussion with Will, we felt that this approach really emphasised the link between indices and logarithms, something that we both felt had been missed by some students in previous years. We felt that the best way to do this was by talking about functions and their inverses. Yes, inverse functions is strictly a second year topic and they wouldn’t need it for their exams in the first year, but it is the connection that has been lost in the past and the reason students struggle with the topic.

In order to build these links we created a Geogebra file that allowed us to turn on an off a series of functions and their inverses. We had it set up to display a couple of linear graphs, a quadratic and then an exponential – the goal being to draw out that the inverses were a reflection in the line y=x. This had students already trying to tell us what shape the inverse of an exponential should be, before we even introduced what the function truly was. I’ve used a similar approach before, but not incorporated the graphs – so the connections were already stronger than they had been for students in the past.

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The next part of the lesson formalised the notation of logarithms, after which we went back to these questions and rewrote them as logarithms, solving the later ones using our new calculators as we went.

The next lesson began with a recap starter, but this time we took the students a bit further…

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They were all able to calculate the answers on their calculators, but actually explaining why was missing, and there was no real notation or workings out (yet). So when we went back through these questions we modeled taking logs of both sides of the equation, or using both sides as powers with an appropriate base. Then we could discuss that as the two functions that we’d composed were inverses that their effects cancel. All designed to reinforce the links between logarithms and exponentials as well as to lay the groundwork for exponential / logarithmic equations.

In the past we’d found that students can be quite unreliable at remembering the laws of logs, despite the connection to the rules of indices – perhaps down to the split in topics between C1 and C2. On our scheme of work this split is non-existent as we’ve run the topics together. We also decided that to further emphasise the link that we would start with the indices rules and from them actually derive the laws of logs – this might go over the heads of some of the students, but they’d have it to look back and reflect on, plus we knew that there would be a good proportion of our group that would embrace knowing why this rule exists. After doing the product law we let the students try to work out the quotient law, and even to have a go at creating the derivation on their own. This also built on our previous work on proof and on how to construct a solid mathematical argument.

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After we’d derived all the rules, the next step would be usually be to work through a series of examples, with students copying them down. As they’d already done a lot of writing I gave them the complete examples and we went through them with the students annotating why things were happening, and what rule was being used to do these things.

When we introduced ex we got the students to plot graphs in a template that we had created in Geogebra – the idea being that after they had plotted 2x and 3x and examined their gradients at each of the points we had given them that they would see that at each point,  ex has the same gradient as y-value. The group were fairly pleased with their discovery, and it allowed us to give them the reason why e is so special that it has been given its own letter. We did have one query though: “how did they calculate the value of e, so that it is the value that will them give it its own gradient?” – this came from a further mathematician, and that question became his homework.

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Much of the rest of the topic was fairly standard – log equations, hidden quadratics involving exponential equations, but with the addition of ex and ln( ) ≡ loge( ) for the new spec, however we did make one tweak to what will has been taught in the past. We felt that students could not pick up how to add logs to a term that does not have them in so that they can then combine them using the laws. Even just these 4 questions that we started together were enough to give them something to work from in the future.

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Overall we were very pleased with how the teaching of logarithms progressed over the week. In order to assess what we had covered we asked students to complete one of the Integral online assessments. Hopefully as this comes back we will see that students have a greater understanding than we have seen in previous years.

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An update from the start of term

In the recent posts we have been focusing on the statistics elements of the new course. It is now time for an update on the general running of the course and the pure elements.

Firstly some background information on the new A-level group. In previous years we have offered the maths A-level in two different option blocks meaning that we have had two groups of around 10 – 12 students. With drop off as students have dropped from four to three subjects at the end of year 12 this has meant groups of 5 – 8 in year 13. This has now been considered uneconomical so we have been reduced to one option block, as it was thought impossible to combine the two groups at the end of year 12. Of course having had this decision imposed on us, we then had a greater take up of maths meaning a class of 26. The balance of this class is also unusual due to a foreign exchange programme meaning that we have a large number of foreign students joining us for the year (two Swedes, two Mexicans, one American and one Romanian). These students will leave at the end of year 12 leaving a much more manageable year 13 group.

In practical terms the sharing of the content evenly has gone extremely well, with us being able to have frequent conversations about the direction of the lessons, despite the added pressure on my time due to being head of department this year.  This has been even better than expected, as having the dialogue has meant (certainly for me and I hope for Will), that the actual planning of the lesson has been easier as I already know what I want to achieve. We have been careful to make sure that both of us have taught both pure content and statistics content to avoid being pigeon-holed as the ‘pure’ teacher and the ‘stats’ teacher.

Another positive has been the use of technology in lessons. In the first three weeks of term I have already booked and used a computer room more than I had in the previous two years. All of the students have now got their new calculators and we are settling into using them – I even treated myself to a new one, replacing the one I had used since I did my A-levels 16 years ago.

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Our first lesson looked at extending GCSE proof. We felt that it was really important to introduce proof as one of our key themes as early as possible. We asked students to choose from a variety of ideas, both algebraic and geometrical, to see what they could come up with. We then discussed what a proof should look like and worked on developing the skills required to build a mathematical argument. This is something that we will be returning to regularly, making sure that students are getting more accomplished.

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Our first major topic was indices and surds. As this is largely revision of GCSE topics we decided to approach it by setting pre-learning tasks and then developing the knowledge already in place. The tasks we set were the ‘walkthroughs’ from Integral Maths. These walk students through the required knowledge of the topic, introducing ideas and allowing experimentation in an interactive way. Students are allowed as many attempts as required without it being recorded and reported to teachers.

For the indices section of the week we used the online textbook ‘Problem Book for A-level Maths’ being developed by Stuart Price (@sxpmaths on Twitter). We really like the way that this has sections for students who are at different stages of development, starting with technique for those who need more work on the basics and progressing through problem solving to puzzles & challenge. Our grade 9 students had great fun going straight onto the challenge problems, while others were absorbed by the technique section. They were also able to move backwards and forwards if required. There is also a final section for each topic which covers exam style question practice, although we did not get to this – something to use in the future.

For the surds section we used an adaptation of an activity from Integral Maths (pictured below) where students discussed how surds are simplified. We deliberately left some expressions that had not been fully simplified and asked students to present their findings to each other. Additional questions for this lesson were taken from Dr Frost Maths (@DrFrostMaths).

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We have been really enjoying using materials from a variety of sources and with different styles. Students seem really enthused and have been seeking us out for extra support when needed. Our next topic is exponentials and logarithms. The logic behind this is that we wanted students to experience something totally new early in the course. We also felt that they fitted very well together, essentially being two different ways of looking at the same topic. I always felt that the two ends were rather artificially kept apart by the arbitrary barrier between C1 and C2, now I have the opportunity to try and teach them together.

Hopefully I will have time for an update next week!

Will’s Thoughts on the Large Data Set

Will Davies has been working with us on the scheme of work for the new A-level. Over the last few years  he has predominantly taught the statistics content for the A-level courses. Here are his thoughts on the large data set:

“When the new specifications were announced the introduction of these “large data sets” (LDS) left me sceptical, and unsure of exactly how we were going to work with them. With time came a lot more clarity; actually being able to pick over the data sets that were released with the sample assessment material meant we could start to see how they were going to be assessed, and how they might fit into our teaching.

And I have come to this conclusion: the LDS is my joint-favourite thing about the new A-Level – the other aspect being that we’ve been able to tear up the old order of topics and build a curriculum that we feel teaches maths in the most logical order and in the best manner. Being able to combine the applied topics in with the pure topics they depend on is key: e.g. binomial theorem and binomial expansion, as well as teaching variable acceleration immediately after calculus is taught.

I have read on Twitter a lot of negativity about the LDS, and I am unsure why. My instinct says that the reason is because the LDS is being perceived as a separate topic that needs to be taught in addition to other content (that we’re already unsure whether we can fit it all in satisfactorily). As a department, from very early in the process we realised that this shouldn’t be the case – the LDS is not a separate topic, it is instead the tool that you use to teach all the data-handing parts of the course.

Every time you do an example – it comes from the LDS.

Every time you set an exercise in class – it comes from the LDS.

Every time you set a homework – it comes from the LDS.

The more the students immerse themselves in the LDS the more familiar they become with it. Homeworks can be to do some calculations or create some charts (and email them to use in advance where appropriate) then as a group we can discuss next lesson. My other big idea for embedding the LDS into our lessons is to have at least once per week a Show-me / Tell-me starter (regardless of whether the lesson is going to be on stats or not). Students will be encouraged to do a little investigation themselves, then getting the class to discuss together discuss the potential causes (e.g. our outliers). This will be way in which we can as a class build up a bank of interesting observations of our LDS, just like the observation we made when we were examining the MEI sample assessment material.

MEIThis question from the MEI sample A Level assessment – we were drawn to the very long tail at the bottom of the Sub-Saharan Africa box-plot, and wondered which countries were causing this. Looking at the LDS we quickly came up with 3 countries with very low birth rates: Saint Helena, Mauritius, Seychelles – all island nations. Which feels like a nice fact – that the island nations of Sub Saharan Africa have significantly lower birth rates than other countries in that region.

This brings me onto our choice of exam board – the data sets are not provided in the exam, yet students are expected to be able to use some very specific knowledge of them in order to gain some marks in their exams. With the large LDSs (like Edexcel’s weather data) you could study that for a couple of years and maybe still have examined at the key pieces of data.

So, MEI has the smallest large data set (covering information about the 237 countries of the world), and that brings its own advantages – it is printable. The bulk of it fits on 3 A3 pages, and I have created a single A4 page that expands on the Dependency status of relevant countries. So now all our students have a hard copy of their data set to use – meaning that we don’t always have to be in an IT room when we’re working on it. The other major advantage is that on presenting students with the data set they immediately felt that because it actually wasn’t “too big” that knowing it well was going to be achievable.20170908_153408

When it comes to using technology there are various ways in which we plan to incorporate this with the LDS. The ClassWiz calculator is clearly going to be key as, as is learning a bit about Excel. Filters, sorting and a deep look into the inbuilt statistical formulae will all need to take place – not just for the sake of the LDS, but Excel skills are incredibly useful. We’re also going to look to support/enhance teaching & learning by graphing some of the data in Geogebra and Gnumeric. (Gnumeric is apparently a very good tool for creating box-plots although I am yet to explore that any further). I have also built in Excel a sampler tool that will create random samples from the LDs, although it still needs perfecting. When it is complete I will share it here.

When it comes to assessments, starting work on the LDS from lesson 2 means we will be able to include it in assessments from half term 1 – to start with we will make sure we write the assessments so we know that students have seen (in one form or other) what we will be asking about, then we can progressively choose more and more obscure statistics to include. Finally we plan to set students extended projects to do. These like likely asked them to choose some aspect of the data set, be it a group of regions or a groups of fields, calculate some statistics, create some charts, draw some conclusions, and to write up a little report on their findings.

Identifying the smallest data set, and revisiting it weekly for 2 years will give students the best chance of becoming as familiar as they can be with the LDS (aside from dedicating too much curriculum time to it). I suppose the bottom line is that we feel that using the LDS to teach all data topics is going to be such an improvement on using (essentially random) examples that are using a similar approach with our GCSE statistics. In lessons our year 9s and 10s are currently populating their own data-set (containing information about themselves). They have really enjoyed the data collection (although I did receive a complaint from the English classroom underneath the standing long-jump) – now to analyse it!”

Thoughts on Large Data Sets

One of the thoughts that came out of my most recent meeting with Simon was that the choice of exam board will be influenced by the large data set. I had previously been of the opinion that I could leave the choice until January 2018, seeing if any more specimen/mock papers became available and analysing question types. However this would mean not spending as long familiarising students with the specific large data set for whichever exam board we choose. As a result of this I have downloaded the data sets for AQA, Edexcel and both specifications of OCR. I should point out that I am not a statistician, I have taught S1 once and try to avoid it if I can!

I have started to look at the data sets to see which is most useable, and which students will be able to best gain insight into for reproduction in their exams. We want to be revisiting the data constantly, so that students are really familiar with it. This means that portability is important as we will not always be able to access computer facilities.

AQA – Purchased quantities of household food & drink by Government Office Region and Country

The data given is split into 10 regions (under separate tabs), with the average amounts of various foods and drinks per person per week. There is also a tab with averages for the whole of England. Having spent some time in Excel playing around with the data it is possible to fit each region onto a single sheet of A3 paper (total of 11 sheets).

AQA 1Looking at the questions in the specimen paper, students are expected to be able to recall information about the average amounts of certain food groups from different regions. This is something that could only be known by someone who has done extensive work with the data set before, and given the sheer scale of the data is unlikely to be something that you could repeat for all of the different food groups.

AQA2Later questions involving the data set give a small excerpt and ask questions about these. These are much more accessible to students who do not have as much familiarity, but will be easier for those who are aware of the context. For example there is question about the total amount of confectionery purchased, which does not state that it is based on averages.

Total Marks based on Large Data Set in AS Spec Paper: 9 (Out of 80 on paper 2, 160 across the AS)

OCR A – Method of Travel / Age Structure

The OCR A specification looks at the methods of travel to work, broken down into regions, taken from the national census in 2001 and 2011 (separated into two sheets). There is also data about the ages of the residents of the regions (2 further separate sheets). Each tab can be set to cover three A3 pages, so a total of 12 will be needed for a portable copy.

OCRIn the question pictured here it would be advantageous to be familiar with the data set, particularly for part (ii), as there are different codes for the authorities based on their type. If you knew this then you would know how to separate the authorities further and would merely have to explain this.

For the other question based on the data set (not pictured), a summary table has been created. It is not as obvious what the benefits to knowing that data are here, although general familiarity and having looked at possible summary statistics will help.

Total Marks based on Large Data Set in AS Spec Paper: 8 (Out of 75 on paper 1 and 150 across the AS)

OCR B (MEI) – Population data and Olympic success

The first thing to note here is that the MEI specification (OCR B) has taken a very different position to the other boards. There will be three different data sets that will be used in rotation. The data sets that will be used for ‘live’ specifications are not available yet.

MEIThe data set that is available for the specimen papers is far less ‘large’ than the others, reducing to two A3 sheets. The question included here really grabbed me as being interesting – what were the outliers in Sub-Saharan Africa? On inspection, the data that stood out was that from islands, rather than countries on the continent.

This data set seems much more manageable than the others, and over two years I would expect students to be able to become very familiar with it.

Total Marks based on Large Data Set in AS Spec Paper: 7 (Out of 70 on paper 2 and 140 across the AS)

Edexcel – Weather Data

Edexcel’s weather data consists of 5 weather stations in the UK and 3 from abroad, with readings from both 1987 and 2015. I have been able to fit the data for each station, for a single year, on one A3 sheet (total 16 sheets).

EdexcThe questions based on this data set again seemed to not require much detailed knowledge of the readings. In the question shown here it is only the fact that there is one reading per day that will help with part (b).

Of course, as Edexcel has not been accredited yet, this may change.

Total Marks based on Large Data Set in AS Spec Paper: 11 (Out of 60 on paper 2 and 160 across the AS)

Summary

While the use of the data set will only form part of my decision on which exam board to use, I have found the process of sifting through the data sets, and the questions that relate to them, extremely useful. It has also shown me the benefits of this approach. In starting to look at the data sets it is already noticeable how the data is starting to feel familiar. I think that this will develop much more ownership of the data and make structuring easier. Now students know they are expected to know the data set, they are more likely to see the value in using it as part of exercises.

First Attempt at a Framework

On Friday I met with Simon and my head of department Pete to try and create an initial framework of topics for the scheme of work. The target was to have a loose order of topics to cover the first year of an AS course, changing from our previous structure of 3 teachers each teaching individual modules, to a linear structure that will probably be taught by two teachers.

One of the real benefits of moving to the linear scheme will be how much time it frees up compared to our old structure by removing some of the assessment. Previously we have tested students each half term in all three modules. This has been in the form of a one hour assessment based on past exam questions, starting off quite narrow and expanding as more content has been covered. By the time these assessments had been completed and feedback given we were looking at 6 hours of teaching time lost per half term. In a linear system I would anticipate that the assessment could be reduced to a single one hour paper initially, allowing us at least 4 hours more time each half term.

Using the AS topic headings from the freely available MEI SoW we began to organise the topics into a coherent order, focussing on pre-requisite knowledge, and links between topics.

workingHaving a hard copy of the MEI SoW to hand (http://mei.org.uk/2017-sow) was useful as we moved topics around.  It is designed to be editable for any specification and allowed us to focus on the connections between mathematics topics

One of the striking things that came up in the conversation was how we had previously compartmentalised topics. Surds and Indices is a C1 topic, whereas Logarithms and Exponentials is a C2 topic. Yet they are different ways of looking at the same thing and surely if taught together would allow a much better understanding of where logarithms come from, something that I have always struggled to get students to see. As such we have decided that the first thing we will teach is logarithms and exponentials, while at the same time revising the surds and indices materials students should have met at GCSE. This means that students will be meeting something new straight away, hopefully catching interest, but also brings in a link to previous learning.

A provisional model is shown in the diagram below, pure units in green, statistics in blue and mechanics in orange.

first framework

The model we have come up with looks very heavily weighted to the first half term. However of the five pure elements, four should be revision from GCSE. Historically we have taught these as the first half term of C1, a third of our teaching time across the whole course. While thinking about the links in topic areas we discussed how some of the topics (see the right-hand columns of the grid above) might be better spread over the course, with pieces put into different topics to improve connections. An example would be that for transformation of graphs in the past we have taught completing the square early in the course and touched back to how this links to transformations much later. We feel that by expecting to make links with transformations at appropriate points throughout the course as it naturally arises the links should be much clearer and stronger for the students.

Coordinate geometry is another topic that we felt was better split across the year. Tangents and normal will fit in as an introduction to differentiation and circles has strong links to trigonometry.

With the statistics elements of the courses we decided that the large data set should be introduced as early as possible. This meant that we inserted data collection, which is largely about sampling, into the first block of topics. This also got me thinking – I had previously decided that I would not make the decision on which exam board to use until much later. However in order to introduce the large data set I need to have made the decision so that students are used to working with the relevant data.

Mechanics fits in very well with elements of the ‘pure’ maths, particularly with calculus and variable acceleration. This has always been something that I have felt is a missed opportunity in the teaching of A-level maths, it should create a connection and allows us to show the roots of these skills in a real life situations.

This of course is only a first attempt and will continue to evolve as we move forward. At our next meeting with Simon we are going to look at the individual content statements for each topic and to order those, whether within the current structure or moved to further emphasise links.

Beginning to Order

One of the first things I am considering when putting together my scheme of work is the order in which we will teach. It feels like I have performed this task repeatedly in the last few years. My first scheme of work included modular examinations in January, then those were removed so I shuffled C1 and C2 into a single ‘core’ unit. When I moved schools to my current position I wrote a new scheme of work, within which a teacher took control of a single module, meaning that each group had three teachers. Last year I had a slightly smaller job of transferring my existing scheme of work into a new format so that it was on the correct templates.

Should we teach the topics broadly in the order MEI have placed them in their scheme of work (albeit with the statistics and mechanics spread throughout) or re-arrange so that similar content is taught together. In the past, when teaching C1 and C2 as a single ‘core’ unit I have rearranged the content so that, for example, all of the differentiation is together. This has already been assumed in the scheme of work, but should integration be taught immediately after. Perhaps it would be even better to teach them at the same time? This would hopefully create a much better understanding of the inverse nature of differentiation and integration – students could differentiate a curve, then integrate to get back to it, using a point on the original to find c.

A different strategy would be to separate similar content, allowing more structured interleaving. As students come back to a topic, they revise the original content and then build on it. This has obvious benefits of seeing things more than once, but is likely to lead to too much time being spent going back over previously learned content and falling behind as a result. As time is already tight we cannot afford too much slippage.

On Friday I will be meeting Simon and my head of department to start to build up the scheme of work, beginning with this process of ordering topics. I have loosely grouped topics – we now need to come up with an answer to the questions posed above. I am ready with the topics on cards to move around, string to make links between the topics and a blank timeline…

Teaching Structure

Today I met with Simon and my head of department, Pete, again to continue our discussion with how to move forward towards the first teaching in September. The main talking point was what we need in place before we can really start creating a scheme of work.

One thing that has been confirmed since our initial discussion is that the school will want us to enter students for the AS examinations at the end of year 12. This will be school policy for all subjects and, as such, is non-negotiable.

The next decision we will need to make as a department is how we are going to divide up the teaching between two or three colleagues. We are very lucky in that all of our members of staff are confident to teach A-level and keen to do so, but any significant changes to the way we currently operate is likely to mean that at least one person will miss out next year. This of course assumes stability, something that at the moment seems likely but that we can never rely on.

In our current structure each module is taught by a different teacher, so that each class has three teachers. This means that each teacher is responsible equally for the attainment of students across the course. It also means that the content is neatly parcelled out, and there are not too many tricky decisions over when to teach content, although with the core modules some thought has been needed so that, for example, differentiation is reached in C1 before C2.

In my previous role at a different school I abolished the distinction between the two core modules and taught it as one block. Where one topic was included in both modules it was taught at the same time, allowing more time to be focussed exploring ideas around the area as a whole. This led to a better flow, with topics seeming less disjointed. The teaching was split between two colleagues, but taught in a linear fashion with them handing over at the end of each lesson. The applied unit was split across the year, dovetailing with the core content at appropriate times. It would make sense if we were to adopt this model to have each of the two teachers leading one of the applied sections.

A further model would be to have one teacher cover all of the core material and one covering the applied. This is probably my least preferred option given the new split in the applied material between statistics and mechanics. I have heard of this model being used successfully in other schools (although obviously with only one applied option being taught), but have also heard of complaints from the applied teacher about being seen as less of a priority than the “main” teacher covering core.

My instinct at the moment is that the two teachers sharing equally will be the most workable solution, so I will start building on this principle. The next thing to start thinking about will be the order in which to cover the content.