Students use TI-Nspire to construct four types of triangle: side-side-side, side-angle-side, angle-side-angle and right-angle-hypotenuse-side.
Because they are easily able to move points and sides on the screen they can gain a conceptual understanding of why there is only one possible triangle in each case.
The TI-Nspire document includes full instructions for students and there are Notes pages where they are asked to summarise what they have found.
This activity forms part of the OxBox, published by Oxford University Press to support their course 'Oxford GCSE Maths'. http://www.oup.com/oxed/secondary/2010gcse/