I remember the first time I ever heard the gospel. I was probably three or four years old. It was during a family devotional, led by my Dad. I remember him talking about how Jesus Christ was mocked, beaten, and killed. He described how Jesus was righteous and that He was innocent of any wrongdoing. When my father described how the soldiers mocked and beat the Lord, I remember feeling angered that they would do such a thing to someone so righteous. I remember wishing that Jesus had called angels to get Him out of this evil. (I realize now that He could not and I'm glad that He didn't.) It was then that I believe I first felt love for the Lord.
Again, I was a pre-school aged child when the gospel was presented to me. I thank the Lord that He gave me parents who appreciated the importance of the gospel. Of course they taught me other Bible stories, but it was the gospel story that they stressed as most important.
We live now in a day in age where Christianity has been feminized. Too many parents are afraid to discuss the importance and sufficiency of the gospel with their children. Believing that their children may not understand, or that it might be too violent, parents forgo the gospel message. Parents might teach other biblical stories, such as David and Goliath. Or worse yet, they might only teach their children moral lessons, such as not stealing from others. While these moral lessons and biblical stories are no doubt important, the gospel of Jesus Christ should be of first importance. We should not fear discussing the details of Jesus' death because His death and resurrection is so important. Other biblical stories should be explained in light of the gospel. For example, after telling the story of David and Goliath, reinforce it by equating David with Jesus, and Goliath with Satan, for all scripture centers around the gospel message.
Remember that young children learned at the feet of Jesus. I doubt, when Jesus was teaching the children in Mark 10, that he was teaching them moral lessons. He was no doubt teaching them the fundamentals of the faith.
Whether you are a parent, or you teach a Sunday School class, strive to present the gospel to your children in every way possible--For it is the gospel of Jesus Christ that saves.