Multi-Millionaire, Full-time Victim Kaepernick (and part-time sucky quarterback) shows off letter he wrote in 4th grade, just a year ago.

Also traced his Roots back to slavery, sporting Kunta Kinte T-shirt as proof.

Just Do Do it.

Colin Kaepernick’s chaotic workout Saturday has left a trail of controversy — and sources told Page Six that a host of behind-the-scenes issues include a letter Kaepernick wrote in fourth grade, legal arguments over a workout waiver, and even a pissed-off Jay-Z.

The controversial Kaepernick was meant to work out for NFL teams on Saturday in Atlanta, but minutes before the QB was to take the field at the Falcons’ training complex, his reps said they’d moved the session 60 miles away to a local high school. (Eight teams showed up, and Kaepernick appeared in a T-shirt that read “Kunta Kinte,” in reference to “Roots.”)

The stunned NFL then released a lengthy statement Saturday with a flurry of details, including a claim that Nike wanted to be at the workout to turn it into an ad. (The brand launched a Kaepernick commercial last year that garnered controversy, a sales boost and a Creative Arts Emmy.) Said the NFL on Saturday, “Last night, when Nike, with Colin’s approval, requested to shoot an ad featuring Colin and mentioning all the NFL teams present at the workout, we agreed to the request.” But Nike then said it did not have cameras at the workout, and just wanted permission to use the names of NFL teams.

Page Six has learned exclusively that while Nike wasn’t filming, it did have a marketing move up its sleeve — in the form of a branded congratulations to be posted to Kaepernick. The marketing material — seen by Page Six — consists of a letter that Kaepernick himself penned back in fourth grade when he dreamed of having a job in the NFL. “A Note from Colin Kaepernick, 4th Grade,” says the copy, followed by a child’s handwriting in pencil that reads: “I’m 5ft 2 inches 91 pounds. Good athelet [sic]. I think in 7 years I will be between 6ft – to 6ft 4 inches 140 pounds. I hope I go to a good college… then go to the pros and play on the Niners or the Packers even if they aren’t good in seven years.” The letter by young Kaepernick is signed, “Sincerely, Colin.” It then has the “Just Do Do It” tagline, and a list of all the teams that were to be at the NFL’s workout.