[1] He moved from his hometown of Bayamón, Puerto Rico to Dallas, Texas in seventh grade.

[2] He played four years of varsity basketball at Trinity High School in Euless, Texas.

As a freshman, Jackson was teammates with top recruit and future National Basketball Association (NBA) player Myles Turner.

[3] and also his older brother Jalen Jackson He scored 52 points in a 92–91 overtime win over Denton Guyer High School in the playoffs after missing the two games previous with an injured ankle.

[6] Jackson tore his ACL at the end of his freshman season, cutting the year six games short.

[7] As a sophomore, Jackson led Conference USA in scoring with 22.9 points per game on 38.6 percent shooting from the field, combining with Keaton Wallace to form the highest scoring backcourt in Division I. Jackson was named to the First Team All-Conference USA.