I think one would agree that learning Latin puts the classical into 'Classical education' yet some would argue that it is also Greek which makes an education truly classical.
Greek is often begun with two years of Latin learning completed although again, people have differing views upon this, and Greek can be begun at the same time or even on it's own.
In his well regarded book, 'The Latin Centered Curriculum', Andrew Campbell suggests the student begins with koine (the Hellenistic Greek of the Bible). It is known to be slightly simpler grammatically and the child will be more familiar with the Bible translations and therefore it may be an easier introduction to this language.
There is a first volume of a new program called ' Elementary Greek; Koine for beginners' by Christine Gatchell.
This can be found at http://www.opentexture.com/products/greek/yearone/default.aspx although I have ordered my first copy from Amazon in the hope my 13yr old studious son will enjoy it!
This little video is helpful along with all the others there; http://www.youtube.com/watch?v=3gaeIUsPJ-Y
One of the reasons I am posting on Greek is that it is available to study at GCSE level and a few Catholic home educators have done or are contemplating this. It is a thorough course and the board which offers Greek is OCR; http://www.ocr.org.uk/qualifications/type/gcse_2012/classics/classical_greek/
Edexcel board also offers the Greek GCSE too.
One of the best loved Greek text books for this qualification is John Taylor's wonderful work, 'Greek to GCSE'.
Samuel (the studious son!) is currently working through the first book alone and very much enjoying it.
It is well presented and clear, but the best aspect is that John Taylor will gladly send all home educators the answer key!
He is extremely helpful and is willing to communicate through e-mail offering any help which is needed. Samuel has only contacted him twice but it is assuring to know he is available should he run into difficulty. (John Taylor has also written some well known Latin texts which are widely used.)
Should the Greek student be taken by the language, then John Taylor offers a more substantial book n 'Greek beyond GCSE' http://www.amazon.co.uk/Greek-Beyond-GCSE-John-Taylor/dp/1853997048 which prepares for the AS level.
One last addition which I probably should have mentioned first; if you would like your student to become familiar with this wonderful ancient language at an earlier age, then my dear friend Michelle has written and designed some helpful Greek worksheets for younger children; http://thatresourcesite.blogspot.co.uk/search?q=greek