Harris and Klebold were both born in 1981. The pair had met while they were in the 7th grade. Over time, they became increasingly close. By the time they were juniors, they were described as inseparable. There are differing reports: some say Harris and Klebold were very unpopular students and frequent targets of bullying, while others say they weren't near the bottom of the school's social hierarchy and each had many friends. From their journals, Harris and Klebold had seemed to begin planning the attack by May 1998. Throughout the next year, Harris and Klebold meticulously built explosives and gathered an arsenal of weapons. Harris and Klebold left behind several journal writings and home videos, foreshadowing the massacre and explaining their actions, with what they hoped to achieve.