One good way to realise a twizzle as a manipulative is with a piece
of elastic. You need to mark 3 spots on the elastic - say a black
spot for the origin, a blue spot for the end of the unit arrow, and
a red spot for the end of the number arrow.
Make up a few of these elastic twizzles, and see if you can use
them to do simple calculations.
You might want to worry a little about the implicit enlargement
that happens in this solution. Can you convince yourself that this
can be achieved by completely geometrical means?
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the
NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to
embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities
can be found here.