Developing deeper understanding

Progress maps and outcomes have damaged mathematics in WA. By making distinct learning points without a web of links to outcomes, mathematics in WA has become disjointed and subsequently students lack fluidity between topics.

I doubt this is a new complaint and has been a fault of many attempted curriculum reforms, but it has been exacerbated by a renewed focus on assessment and the lack of credible assessment performed in early years.  In many cases a year 10 student can perform a percentage calculation if (and only if) it is preceded by 10 examples of exactly the same type.  A student can get 80% in their test by teaching study skills for a percentages test and by creating decent notes... but do they have an understanding of proportion and how it applies to percentages?  In many cases they do not.

As a teaching group we have been talking about percentages (as OBE pushed many decimal concepts into high school and they are now being pushed back by national curriculum). It is important to learn how to teach it more proficiently in lower school and to our lower ability upper school students.  One of the more successful ways we have encountered is to use relationships with ratios.

Problem: Find 50% of 50.

Using a ratios approach
100% of an object is 50
50% of an object is x

To get from 100% to 50% we have to divide by two (100% ÷ 50% = 2)

100% ÷ 2 = 50%
thus to stay in proportion
50 ÷ 2 = 25


Using a paper strip it is easy for students to see the proportions in action.

They can readily see that 50% is between 0 and 50.  It's easy to experiment with a wide variety to proportions and it readily extends to percentages greater than 100%, percentage increase, percentage decrease, finding percentages given two amounts and negative percentages.


Using a formulaic approach
Take the percentage, divide by 100 and multiply by the amount.
or
Take the amount, divide by 100 and multiply by the percentage.

I know which of the two approaches is quicker and easier to teach.. but to extend the formulaic approach to other types of problems requires new sets of rules to remember and apply.  Without a basis of understanding it becomes difficult to know which formula to apply and when to apply it (unless it was proceeded by a worked example - which leads us back to the original concern).


Using ratios and an algebraic approach
x ÷ 50 = 50 ÷ 100  (rewrite ratios as an equation)
x = 50 x 0.5  (multiply both sides by 50)
   = 25

Once students understand some basic algebra and proportion, the solution becomes trivial (as it is for many of us).  Sadly many students today do not reach this level of proficiency.  I'm sure there are other more effective and efficient ways to teach proportion and percentages (and even some that don't use pizzas) but I think my point is fairly obvious.




I think sometimes we can get carried away by the need to meet an outcome and teach the how (as is driven by a packed curriculum) rather than using an exploratory approach that provides students with understanding which can have lasting consequences (often unseen by those that don't teach senior school topics).  I originally saw the paper strip approach (or something similar) done by Keith McNaught at Notre Dame university.  It has stuck with me throughout my teaching.  When I am tempted to get curriculum dot points completed and tested (disregarding deeper understanding), it is always a good reminder of what should be done.

As a final note.. I do believe that nothing replaces practice and students need skills based work that requires rote learning (such as what is done with the formulaic approach).  Which means as teachers we have to get better at providing pathways through the why (such as via the ratio method and with formal proofs) into the how (such as with formulaic approaches) and then making connections to other techniques (as seen with the algebraic approach) - always remembering that students shouldn't have to re-invent wheels which in many cases took millenia to form.

Review of material written

Well, one thing was obvious.. the 3A MAS kids aren't quite at the level expected yet.  We barely reached unit vectors which meant that we didn't get to the meat of the topic.  This was a shame as the helicopter example is a great example of how vector topics fit together.   It has indicated next time I need to go a bit further backward and put a few more examples in for unit vectors.  We also need to look at the difference between adding and finding the difference between two vectors.  Possibly also looking at examples of each in action. Easy fixed.  The year 9's and 10's were comfortable with Linear functions and could use difference tables capably according to the tutor, if anything the work was a bit easy!  This is good news and unexpected! 

Unfortunately the 2C finance EPW was as expected and underlines that the group is a bit weak.. the students stopped after they thought they had learned something, which meant that they didn't get to the meat of the assignment (rookie mistake!).  I think in more than a few cases social life and sporting interests come first.   One student had done the work.. the rest were a bit of a shambles.   My feeling is that the EPW is right, we should be able to make an assumption that year 10's have done compound and reducible interest and (with a bit of revision on their own) should be able to answer reducible interest problems with a calculator.  One in the 80's, a couple of high forties and that's about it.  Very disappointing result but hardly surprising given the incomplete take home sections.  Hopefully what they have done will help them understand it properly when the topic arrives.  These are students entering 3A and they can't be spoonfed and expect to do well.

Writing lasting material

It makes me laugh that we invest time in our teachers, but rarely invest time in the resource bank of a school.  This causes a massive information loss each time a staff member leaves the school and requires significant effort to regain capacity back to the previous level.

We are at present putting material together for our after school classes and the lack of extension resources is amazing.  The most common response is that extension classes after school are usually just repackaged classroom material at a higher level.

This can't be right.  If a student seeks extension it's because they want material not found in the classroom - this is one aspect of summer school success we have.  We don't just teach year 11 material to year 10's, we repackage it such that it is context specific, timely and interesting.  One of the joys of an after school class is that you are not confined by syllabus and delivery points and you can delve into topics in a little more detail if students are interested.  Hopefully students that didn't quite get it can now see where the majority of students are.  Students that have a solid understanding can draw connections to other areas of mathematics and other learning areas.

I believe the resources I seek have been written and are sitting in drawers around WA.  I understand why teachers are proprietary about their resources.  Little time is given to developing resources and they have to be done in your own time.  DOTT is taken up with marking, meetings, behavioural resolutions, recouping sanity time and parental contacts.  It leaves little time for planning and developing of resources.  If schools were better able to value what after school programmes could achieve, monitored what they did achieve, set goals to maximise future achievement and provided time to prepare resources to meet these goals then just maybe a few more students in the middle would find success and a few more high achieving students may be able to seek the stars.

Given the changes in curriculum, I'm not writing material to fit state or national curriculum, IB or NCOS.  I'm sticking to topics that can be used across year groups and ability levels.  The first two topics students have asked for are Linear functions (lower school) and Vectors (upper school).  I've designed a written format and a method of delivery and I have some material on Finance that I can bend into this format.  We'll see how it goes tomorrow and Tuesday.

There are opportunities "beyond the classroom" where schools can and do make real differences.  It's a shame that all too often it is because of individuals rather than by initiatives by the school itself.

CAS calculators

The importance of using calculators appropriately cannot be underestimated.  Percentages and compound interest are two of the most misunderstood topics in year 9 and 10 and many student errors could have been prevented with effective use of calculators.  This year my year 9, 10 and 2C classes all did compound interest at about the same time.  All three classes were able to use the CAS calculator to construct the equations required for reducible interest. 

Teaching calculator usage in year 9 should prevent some of the errors in year 10 and 2C because:
a) they will not be struggling with "how to use the calculator" next year (modes, cell referencing & formulas)
b) they will be able to calculate percentages of amounts with or without a calculator
c) they will be able to work with the idea of a period of time and know that this needs to be consistent across an equation
d) they will be able to work with interest periods other than annually
e) they will be able to identify simple and compound interest problems

There are many times calculators are inappropriate but in this context it is an engaging tool and the novelty helps focus students on a fairly dry topic.  It is unfortunate that the 2C class did not have this benefit as they are struggling with remembering what compound interest is and how reducible interest relates to it.  Finding time in the curriculum to promote appropriate usage is well worth the effort as this is one of the occasions where a calculator/spreadsheet is used in a real life context over pen/paper.  A good series of worksheets can be found at classpad.com.au under the intermediate tab.  It does take some patience but students will quickly learn how to create spreadsheets well.  I would also show students how to use the fill range tool (under the edit menu) to make the process a little quicker.  It may be worthwhile to use MSExcel first in a computing lab.

It is obvious that many students have not seen how spreadsheets can be used in computing classes or are not making the cross curricular connections of how that knowledge could apply in mathematics.

A byproduct of the classes is that it was a good assessment checkpoint to see if they understood how to apply percentages of amounts and whether students could see how it fits within a multistage question.  The tens did very well making the transition from spreadsheets to the compound interest formula and I now anticipate that it will be an easy transition to finance mode for more complex worded questions.