On a playground, a sandbox is a place where the dirt is cleaner than the dirt that is found naturally around it. No roots, no weeds, less dangers. It is a created space, where the environment is different.
One method of creating leadership is to create space in front of a younger generation in which they can sandbox, to learn and create and fail and learn. Trusting them with things that would be beyond their reach without the help of the Holy Spirit can teach them to listen to Him. Trusting them in a space where the current leaders are present for advice and repair is a safe place for them to learn to make decisions and to follow through with them to discover the outcomes they produce.
Frequently the narratives about the ministries of Jesus imply that He sent disciples out to fulfill assignments and taught them how to do it when they returned with questions their experiences had prompted them to ask. Our methods are usually to give classroom instructions, written exams, and then exercises in labs before we trust anyone with real work. They have to prove something before we trust them with responsibility.
His plan seems to be to teach them to listen to Him.
In that same hour He rejoiced in the Holy Spirit and said, “I praise You, Father, Lord of heaven and earth, because You have hidden these things from the wise and the learned and have revealed them to infants. Yes, Father, because this was Your good pleasure. All things have been entrusted to Me by My Father. No one knows who the Son is except the Father, and who the Father is except the Son, and anyone to whom the Son desires to reveal Him.”
Then turning to His disciples He said privately, “The eyes that see the things you see are blessed! For I tell you that many prophets and kings wanted to see the things you see yet didn’t see them; to hear the things you hear yet didn’t hear them.” (Luke 10:21-24 Holman Christian Standard Bible ®©)