The Catechesis of the Good Shepherd program is an outstanding means of teaching young people about the real presence of Jesus Christ in the Eucharist. From their website:
“The 3-6-year-old child is particularly capable of receiving and enjoying the most essential elements of our faith—the announcement of God’s love especially experienced through Jesus, the Good Shepherd, who died and is risen. Materials on the life of Jesus Christ and his teachings help to make the mystery of God concrete for the child. The heart of the catechesis for children under six revolves around the Parable of the Good Shepherd. Jesus announces that he is the Good Shepherd who calls each one by name. The sheep listen to the voice of the Shepherd and follow him.
“The 3-6 year old child enters the mystery of the Eucharist by first learning the names of the articles used on the altar and then through the most important gestures including the preparation of the chalice, the epiclesis and offering, and the sign of peace. Through the experience of seeing these gestures, presented one by one, the Mass emerges as the Sacrament of the Gift. The child becomes acquainted with the historical character of the liturgy through the events of the Last Supper, Christ’s death, and His resurrection.”
One story is that of a teacher in a 3-year-old Catechesis of the Good Shepherd classroom noticing that Jesus was missing from the manger. The teacher called the children together and asked if anyone knew where Jesus went. One little boy sheepishly admitted that he put Jesus in his house. “Where is that?” the teacher asked. The boy went to the tabernacle, opened it, and there was Jesus. The child then asked, “Isn’t that Jesus’ house?”
The connection between the child Jesus in the manger and the Jesus in the tabernacle being the same person can even be taught to 2-year-olds.