Harris, Paul: Improve your sight-reading! Descant 1-3
sheet music
Step-by-step it helps the player to build up a complete picture of each piece, first through rhythmic and melodic exercises related to specific problems, then by the study of prepared piece with associated questions for the student to answer, finally, to the unprepared sight-reading test itself.
Check-boxes for each stage allow both teacher and pupil to keep a eye on progress.