I would like to know if anybody has experience with the British textbook series Extension Mathematics in three volumes, by Tony Gardiner.
It claims to be "the first structured KS3/S1-S2 programme for gifted and talented students." (That's ages 11-14.)
First of all, is that true? Are there really no comparable books, even older ones?
Are these books well adapted to students who are, say, in the top 1% of ability, rather than 10-20%?
And are there any books with the same objective but designed for KS4 (ages 14-16)? Perhaps older O-level books?