How does someone become a missionary?
Explain that only someone who is a believer may be a missionary. Use the opportunity to invite any in your class who may not be saved to trust in Christ.
Stress the importance for all believers to maintain a close walk with the Lord, whether they are interested in becoming a missionary or not. The missionary, however, will sometimes find himself in a situation where he has no choice but to trust in God. So teach them to start now!
Missions boards and denominations have different requirements for someone to serve as a missionary. If you are a part of a denomination, find out what they are. If not, get information from several missions boards that send missionaries your church supports.
Have a child in the class roleplay a missionary preparing to serve or, better yet, have a missionary on furlough come to your class and explain the steps they had to go through to get to the field. This will encourage those children who may already be thinking of a life career on the mission field.
By the way -- don’t forget home missions!