free websites I like

These are some of the websites I like. Apologies for missing out some other good ones - I'll collect these together later (for myself at least):

• 'ptolemy' (Alec Mc Eachran) is a fine site ('primitives' being an excellent way to view an image of numbers - with their factor properties); it has links to Mandelbrot (great zooming in to a Mandelbrot set on Vimeo) and a Utah genetics site, for visualising tiny things (and powers of 10)

• 'teacherled' (Spencer Riley) has many excellent and very well presented whiteboard resources, leaving teaching - rightly - up to the teacher. Particularly like (most of it but, at the moment): reptiles (fitting 4 similar shapes together to form an enlarged version); shape exploder (making it easy to count the number of cubes in a cuboidal (invented word) solid); dice (roll up to 3 dice, in space (which could get irritating...)); rotating around a point (I like sliders... and this shows a rotation beautifully)   

• the Primary, national strategy ITPs are good and are easily viewed and used from this index

• the Cymru ngfl site has many good (and some not so good) resources, I particularly like the resources produced by Dr Iestyn Jones (of 'eChalk') for 3D investigation and geometrical transformations and some of the investigative software (e.g. painted cube). The 'geoboard' for Pick's theorem etc is lovely (go to the 'develop' section/tab for DIY shapes).

• NLVM has a really good collection of virtual manipulatives - saves picking pattern blocks up from the floor

• pedagoguery software has poly (1.11) as a download which creates foldable nets of polyhedra

• mathspig (blog) (Kerry Cue) contains a healthy look at maths in the media with applications of maths that are actually interesting (as opposed to functional maths efforts that take some reading and then only evoke yawns)

• Matt Dunbar's 'estarters downloads' is a fantastic use of Excel (how does he do it?) with quite a few free downloads (including fine demonstrations of Pythagoras)

• the 'geometry toolbox' is good for simple constructions