Take any spider and have it run "next to" (as in a movable line away from) a spider of the other colour. Repeat the following step 3 times: "Mentally move backwards along the lines till you hit the next spider, and move it next to the previous one" this should end by putting a spider in the right place Repeat the following step 3 times (all of which end with aligning a spider to it's right colour): "Mentally move backwards along the lines till you hit the next spider, and move it next to the free space before the previous one"