Blessed Assurance: How to Know?

And we desire each one of you to show the same earnestness to have the full assurance of hope until the end. (Heb. 6:11 ESV)
Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you? — unless indeed you fail to meet the test! (II Cor. 13:5 ESV)
You're giving a talk to the youth of your church (6th - 12th grade) and their parents. Your topic - The Assurance of Salvation: Ya Got It?
OK, so now what? What resources would you reference in your preparation? What references might you suggest and recommend to the parents to go through with their youth?
And what would you say to these kids about assurance? Can you have it? Keep it? How to fight against the doubt of one's salvation? How can you be sure that you're even saved in the first place?
Love to hear your thoughts.