Category Archives: Core

251. Safe as trees

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Here’s a two in one post for you, with a wooden theme:

safecracker

Tree 1

This fascinating wooden puzzle is available on Etsy. Each line has to add up to 50 – simple? Not as easy as you’d think. A perfect classroom extension puzzle or gift for a puzzle fanatic!

Tree 2

A little starter on logarithms, with a touch of safecracking too!

Crack the safe Logarithms

The questions are sourced from an A-Level textbook – why not make your own textbook tasks more interesting by creating your own safecrackers on the board? Five minutes prep = puzzle fun!

244. Resource of the Week

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I recently came across this splendid resource for introducing Sine and Cosine rule to students.

Proving the Sine and Cosine rule

The proofs for these rules are relatively simple, but getting a class of teenagers to engage with it is a different matter! These worksheets give you the proofs, step by step, but all jumbled up. Students must rearrange the stages in order to create a proof. It worked brilliantly!

Thank you @mrslack_maths

 

239. Introduction to Arithmetic sequences

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Here’s a quick post for all those of you teaching Arithmetic Sequences. Whether you are teaching Level 3 Algebra or the C1 A-Level module, the jump from GCSE Nth term to the form ‘a + (n-1)d’ can be unnecessarily tricky. To help with this I’ve written a starter booklet for Arithmetic Sequences. You can download it here:

Introduction to arithmetic sequences

By the way, if your students confuse the vocabulary ‘sequence’ with ‘series’ get them to think about television. A normal television series ends, so an arithmetic series must end too!

237. Quick Starter

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Don’t you just hate it when students forget basic key skills? Especially those at the higher end of Year 11 or studying A-Level, who should have a better core knowledge. What if there was a magic tool which began to address this issue?

Skills required

  • Comparing fractions
  • Trigonometric ratios
  • Simplifying surds
  • Rationalising surds
  • Pythagoras

Equipment

You will not need:

  • Worksheet
  • Powerpoint
  • Printer
  • Laminator
  • Calculator

Magic Tool

  • One board, with pen

Activity

Quite simply draw the four diagrams below on the board and ask the following questions:

Triangle Problems

  1. Which has the largest sine ratio: A or B?
  2. Which has the largest cosine ratio: C or D?
  3. Which has the smallest tangent ratio: A, B, C or D?
  4. Extension: Calculate the missing angles and areas (Calculator allowed)

It takes moments to draw the questions on the board, but the discussion can take some time and addresses several basic skills. You can change the numbers to adjust the level of challenge.

211. Hidden Rectangle problem

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Cool vectors can be exciting! They can describe the motion of a particle, they can represent the acceleration of a rocket, they can tell you about the angle an impact takes place at!

3D axes

Uncool vectors describe lines, they can intersect, they could be perpendicular, they could even describe skew lines in three-dimensions. Not quite as exciting. It isn’t difficult to see that revising standard C4 vectors can be a tad dull. How about an investigation? An investigation without an obvious answer. A question so simple that the answer is a single number. It’s the steps in between that make things interesting…

  • I asked my A-Level class to find the area of a rectangle … simple so far, how is this worthy of C4?
  • The rectangle is bounded by four vector equations … ok, points of intersection, line segment length, bit of Pythagoras there
  • The vector equations are 3D … ooh, that makes it a bit harder
  • There are eight equations to choose from … that’s mean, that means finding the angle between lines, checking for skewness, identifying parallel vectors
  • There are plenty of ‘red herrings’ … now that is just unfair (great!)

The solution to the problem is a simple surd. If you do ‘Crack the Code’ or ‘Locked Box’ problems you could use the digits under the square root sign as your padlock code.

You can download the worksheet and teachers notes here: C4 Vectors Hidden rectangle (pdf)

Depending on the engagement/ability of the students this could take between 20 and 40 minutes. It would also make an easy to assess homework.

207. Is it on the formula sheet?

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In the Autumn term I put together a booklet of all the Trigonometry and Differentiation rules that you need for the Core 3 (Edexcel) exam. It was a summary of key facts and highlighted what you need to learn vs what is on the formula sheet. The original post was 155.Trigonometry&Differention including links to the booklet.

One term on, at the request of students, I’ve produced the same kind of booklet for Core 4 Integration and Differentiation. Even if you don’t do the Edexcel exams, they are still helpful revision tools.

You can download the booklets here:

C4 Differentiation & Integration (docx)

C4 Differentiation & Integration(PDF)

 

204. Revolution in Volume

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Most elements of Core Maths can be visualised with a good diagram, but volume of revolution can be tricky if your technical drawing skills leave something to be desired. My colleague JA came up with a visualisation which is simple and elegant, yet also fun and memorable.

Step 1
Start with a curve. Introduce the limits a and b. Discuss what shape a thin strip would make: a disc.

image

Step 2
What would several discs make?
Now this is the cool bit:

image

This innocent looking shape is a pop up gift tag:

image

You can demonstrate what happens if the curve rotates 180 degrees around the x-axis.

Step 3
Now the really fun bit: dig out those interesting honeycomb christmas decorations, a metre stick and some tape:
image

The metre stick represents the scale on the x axis. The decoration represents the full 360 degree revolution about the axis.

Hint
Since these decorations are made from paper and card. You can use a sturdy craft knife to cut them into other curves. They also make great wall displays.