Aptitude

What are aptitudes?
How can it be measured?
Is the concept a useful one in the EFL classroom?
Please integrate my 8 pages in this essay.
to what extent have aptitude has influence on SLA.
I also need a table of content and a list of references
I would have some helpful articles as well: Richard Sparks and Leonore Ganschow (2001). APTITUDE FOR LEARNING A
FOREIGN LANGUAGE. Annual Review of Applied Linguistics, 21, pp 90-111.

Peter Robinson (2005). APTITUDE AND SECOND LANGUAGE ACQUISITION. Annual
Review of Applied Linguistics, 25, pp 46-73.
doi:10.1017/S0267190505000036.

Charles W. Stansfield and Paula M. Winke (2008). Testing Aptitude for
Second Language Learning. Encyclopedia of Language and Education, pp
2226-2239.