Thinking about teaching functions in the next few weeks (to UK Year 12 ages 16-17) I realised that I could use Desmos to illustrate composite functions; the following slideshow illustrates the syntax.

We can also use Desmos to illustrate a function and its inverse. To create the page below (select the image), I started with a graph already online illustrating the general case of a quadratic function and its inverse and simplified it. f(x) and g(x) can be changed to a different function and its inverse. Note that the domain of f(x) can be changed.


Further examples: exponential function and basic quadratic (where we need to restrict the domain for an inverse function to exist).

Staying with Desmos, as I have mentioned before, the function notation is excellent for transformations:

(See this page for all Desmos slideshaows).

IFunctions two argumentst is also possible to define a function with more than one argument and use Desmos as a calculator

For some clear examples and a resource to point students to, Functions from The University of Plymouth Mathematics Support Materials is useful. The format used in this series makes the examples clear and all the exercises given have answers.

Functions - Plymouth University

Functions – Plymouth University

Other useful resources (requires Java) include the Wisweb applets, algebra arrows could be used to demonstrate functions and their inverses as shown in the following images. (There are issues with Chrome and Java, it may be better to use IE or Firefox.)

This slideshow requires JavaScript.

Numberlines - Mark Robinson

Negative Numbers – Resources

Sometimes resources for younger students can be useful for lower secondary age students, see for example Mark Robinson’s Numberlines  from the old Ambleside Primary School site which includes an option to display a number line from -5 to 5.

For another excellent number line resource see J Barrett’s Numberline Jump Maker on I often recommend that students sketch a number line to help with addition and subtraction problems and very clear resources like these can really help. Teacher Resources on Line includes a Big Number Line under Basic Materials for display on a classroom wall

Games can be an excellent way to practise with negative numbers see for example games such as Connect 3 from Nrich and Tic Tac Go, a Wisweb applet.

Further resources include exercises from Trinity School in Nottingham (under Number) and Interactive Resources from CIMT (see unit 3, 3.3 on Negative Numbers and Unit 15, 15.1 and 15.2 for operations with negative numbers in the tutorials section).

There are many excellent resources on TES, the resource collections includes a section on Topic Specials which includes 10 of my favourite resources on Negative Numbers.

Plans and Elevations – Wisweb Applets

Update – a new environment for the Wisweb Applets – these work beautifully in modern browsers.

This week I need some resources to demonstrate plans and elevations. There are several Wisweb applets from the Freudenthal Institute which are excellent for this topic. These work well on  the interactive whiteboard for demonstrating to students, they are also ideal for students to explore themselvesJust in case you  get a Java error message even though you have an up to date version of Java installed then you need to Configure Java (see your programs list) and under the Security tab add an exception site: site address here. I left my security setting as high and this did solve the problem.

Cube houses shows several models with their elevations, select drawing then 3d-model to give a model you can rotate  to generate different views.

Readers familiar with the excellent Improving Learning in Mathematics materials may recognise the applets for building houses; these are described in SS6 – Representing 3D shapes which has suggested lesson activities and describes the applets (see pages 4 and 5).

Building Houses allows you to create buildings and see the plan, front and side elevations as you build. (If that link does not work – try this).
You can add (build) or remove (break down) bricks and control the size of the square base.

Building houses with side views challenges students to construct 3D models given the plans and elevations; the task is made more challenging by specifying that as few cubes as possible should be used.

Note that in order to achieve the minimum number of cubes, ‘floating’ cubes are needed.

Note that these resources have been added to the ‘explore‘ series of pages on the companion blog for students.
Update – these resources worked well with my students – they particularly enjoyed the challenge of trying to build models using the minimum number of cubes!

Readers interested in the Improving Learning in Mathematics materials further may find IWB Resources  useful as it has a flipchart and notebook file for each of the activities. This site is a result of the NCETM research project: Enabling enhanced mathematics teaching with some interactive whiteboards (September 2006- September 2008) and is supported by the IWB research team at Keele University and the team. See also the link on the reading page to Malcolm Swan’s Improving Learning in Mathematics – Challenges and Strategies.

Wisweb Applets

Update – a new environment for the Wisweb Applets – these work beautifully in modern browsers.

I can see from the WordPress statistics for this blog that people often end up here searching for the excellent WisWeb applets.
For further details on the plans and elevations applets see this post.

Try this applet  which shows how a solid is formed from a net, just move the red slider from 0 to 100.

Using  Algebra Trees form inputs, operations and output by dragging them onto the main workspace, connect them up and optionally connect to a graph. Click inside any of the elements to change the content.

Once you have tried a few of these applets you will find them intuitive to use.

Algebra Arrows for example could be used to compare different orders of operations. Build a tree, make the input x and note the output generated:

There are several applets which are excellent for showing plans and elevations, see for example Building Houses with side views where the user must construct a house given top, front and right views. Teachers familiar with the ‘Improving learning in Mathematics’ materials will recognise some of these applets.

Solving Equations

There are many excellent resources online for solving equations.

A simple way to see a complete solution to an equation is to enter it into WolframAlpha then select ‘Show Steps’. (Update 2012 – using the free version of WolframAlpha allows you an unlimited number of queries, so excellent for checking any work but you can only use ‘Show Steps’ three times a day!)

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