Teacher Notes

This activity could be introduced in a lesson and set as a piece of homework, although I used an hour lesson since the sharing of ideas proved invaluable.  I gave this to a bright class of 15 year olds who knew the general formulae for arithmetic and geometric sequences.  They had no previous experience in using the Ti Nspire.  Given that we do not have class sets of the handheld devices they downloaded a 30 day trial version of the software onto their computers.  I was really impressed with how intuitive they found the software and the short video really helped them to see how to input their formulae into the software and link it to a graph.  You could give your class the .tns example file and get them to edit the formula in one of the cells, but I would recommend that the students create their own files from scratch.

Using the split screen to see the algebraic formula next to the numerical sequence and the graph really help to cement their understanding of these types of sequence.  Students can make small adjustments to the parameters of the formulae that they enter and gain a deeper understanding of what their effects are.  I love the way the technology allows them to play with their ideas.

There was a lovely discussion between the students when they were comparing their answers to question 2.  Both students argued vigorously that their result was correct

The technology showed that they could both be right and encouraged them to justify to themselves why.

The answers to this activity can be found here