Color blindness is a condition that affects the cones in the eyes; it can be congenital or acquired and is considered an average disability that affects about 10% of the world's population. Childrens with color blindness have particular difficulties when entering an educational environment with materials developed for people with normal vision. This work focuses on modifying the Ishihara test to apply it to preschool children. The proposed test helps to identify children who suffer from color blindness so that the teacher who guides them in the school can attend them.