"Her final lesson was about serving others. That [was] what she had done her whole life," her cousin, Dr. Brad Johnson, wrote to ABC.
Waddell, 58, had beaten colon cancer once and was in remission but complications came up, Johnson said. When she learned she might not make it much longer, she discussed the backpack idea with her family.
When Waddell passed away earlier this month, the family shared Waddell's wishes in her obituary. Donations came in from around the world, Johnson said.
At her funeral, about 100 teachers served as "honorary pallbearers." Johnson said the teachers, who had all worked with Waddell over the years, brought the backpacks with them back to their schools.
Waddell worked as an elementary school teacher and paraprofessional for three decades.
"She was the kind of teacher who always had a hug for students who needed it," Johnson wrote. "She often spent her own money on supplies to give to the students who needed it."
She leaves behind a big family including a husband, two kids and four grandkids.
Johnson tweeted that backpacks are still being accepted in Waddell's honor.
back packs can be sent to: pic.twitter.com/62D6ALVF7L— Dr. Brad Johnson (@DrBradJohnson) June 25, 2018