After some studies on students with Down syndrome (DS) who learned algebra and problem solving and few single case studies on analytic geometry, here the experience on analytic geometry was extended to 6 adolescents with DS, who attended mainstream schools. They were taught individually in the afternoon, one day per week, for 9 months by the same teacher, who also graded their performances during the course and in a final test. No preselection of the participants was done, except for the chronological age. The programme was: fractions, positive/negative numbers, linear equations, the Cartesian plane, the equation of a straight line, parallel and intersecting straight lines, the belonging of a point to a straight line, and the distance between two points. The use of a calculator and a ruler was allowed all times. As a result, almost all the students learned to work autonomously on each topic of the programme. All the students either improved or maintained their performances from the course to the final test. One student with a severe impairment in speech, reading, and writing was able to learn and to enjoy the programme. This study confirms the previous results and should be extended further.