Jesus didn’t say, “Show up to class and I will train you.” Nor did he say, “Attend synagogue and that will be sufficient.” No, he called the disciples to join him on the mission (“Follow me”), and while they were on the mission with him, he trained them to be disciple-makers (“I will make you fishers of men”).
In other words, Jesus taught them the basics of making disciples while they were on the mission of making disciples. They could observe everything Jesus said and did. They could see how he rebuked the religious leaders who tried to make it harder for people to come to God. They were able to watch his compassion and care of people being ruined by sin. They couldn’t overlook his willingness to heal and help the broken. And the power he exerted over demons was clearly on display. They listened, watched, and learned in the everyday stuff of life. After a while, he invited them to share in some of the work he was doing. Sure, they messed up, a lot, but he was there to help, to correct, to clean up—to train them—while they were on his mission. They were in a disciple-making residency with Jesus.