Nobel laureate Barbara McClintock discovered a “tiny fragment” chromosome, which she postulated contained an “X component” that could rapidly reorganize the genome. This fragment chromosome rearranges itself as well as other regions of the genome. The regions that would participate in these rearrangements are now known to contain highly repetitive sequences. They present a challenge for the DNA copying mechanism that is often stalled in repetitive sequences and needs to be reinitiated. If this reinitiation is defective, DNA breaks occur at these sites and could form the basis of the rearrangements produced by the X component if the breaks in various places in the genome occur simultaneously and are eventually repaired with swapped partners. The types of rearrangements produced are similar to those that commonly occur during karyotype evolution, so an understanding of the X component will reveal a novel genomic activity that can have a profound effect on chromosomal changes. An educational program is proposed to digitize microscope slides of chromosomal aberrations and their behavior from an historical collection and an instructional video on the technique of whole chromosome painting in maize will be produced and uploaded to the laboratory Youtube channel. The proposed experiments will test the hypothesis that dramatic changes in transmission frequency of the tiny fragment chromosome are the result of genomic rearrangements catalyzed by the X component carried on the minic