From MEI we have valuable advice and tasks on using calculators in the new A Level specifications.
See also these Calculator pages including manuals and clear instructions on how to use the calculators:

Calculators – Collections
These calculators can be used in class to demonstrate calculations and check answers, see for example this calculator from Math Warehouse for solving a quadratic equation showing full working.

Quadratic Formula

Math Warehouse

Return to the Tools and Calculators series of pages or Lesson Planning.