I don't like bash people who came before me, but I will say that I don't think my predecessor had the teens do any kind of study at home. We did a topical study of Hosea and I asked them to read the chapter for next week ahead of time so that we could just read high points in class and stick to a topical discussion and not a verse-by-verse. I got deer in headlights and an audible scoff. "We're busy", "I have school work", "not enough time", were the answers I got. I couldn't believe it! 7 days, and you can't find time to read 26 verses of God's Word? When I was a kid (back in my day, youngins) we had a notebook we had to keep that our youth minister checked and gave to our parents. We also had tests, which were graded and went to our parents. I told them that and their eyes nearly popped out of their heads!
I'll definitely get working on them doing some personal reading/study and reflection.
Excuses, and horrible ones at that. Let me tell you what I would do, though you may prayerfully discover different strategies for your own group. Two weeks ago, I was 5 weeks in to teaching my study group the essential doctrines of the faith; that is, the doctrines necessary to accommodate the three stages of salvation (namely, justification, sanctification and glorification). I had believed we were ready to move onto doctrinal teachings and was zealous to prepare the group for understanding and defending these doctrines according to the command of Titus 1:9. The irritability, impatience and lack of passion I noticed in some of the members however made me realize that I needed to return to the raw Gospel directly, and use the following weeks that the divided sections of Gospel would endure as every opportunity to address the balanced message of God's grace in light of God's wrath, and how the Son satisfies so fearsome a requirement on our behalf.
I always remember Jesus' admonishment to "as shrewd as snakes, and innocent as doves (Matthew 10:16)." Likewise, Jude's admonishment to "Be merciful to those who doubt; save others by snatching them from the fire; to others show mercy, mixed with fear—hating even the clothing stained by corrupted flesh (Jude 1:22-23)." It is important to remember, not knowing the hearts of anyone, but knowing only by their fruit (Matthew 7:16), that some, despite attending Bible class, have not believed unto salvation; others may sincerely know Christ, but have become slack and need encouragement (whether soft or tough love). Thus it helps to revitalize an appreciation for why the Gospel is such good news. This may require more of a "come to me, all you who are weary and burdened" orient (Matthew 11:28), or rather a "unless you repent, you too will all perish" orient (Luke 13:3). This may seem harsh, but we have to remember our Lord thought it fit to speak this way, and left His words as both comforts and warnings for our benefit.
It is difficult to feel the worth of grace until you feel the weight of what that grace saved you from. Was it merely from having the feeling of an insignificant life? Was it from bad conscience, or lack of substance or answers to life's questions? No, but it was from eternal separation from God. If this is truly and comprehensively understood, one can not help but respond with joy and gratitude to the word of God (Psalms 30:5, Psalms 84:2, Psalms 119:20). So it will be on the basis of God's love, grace and mercy in light of God's righteous judgement against sin that one will find their stone heart transformed into a heart of flesh (Ezekiel 11:19), to be impassioned for their saviour or to know Him for the first time.
If they grasp this message of the Gospel of Jesus Christ and it penetrates into their heart, excuses will disappear and you might find yourself instead burdened with the ministry requirements of a group so hungry and thirsty for righteousness.
I want you to take note that I have no intention of appearing as though I think to instruct you ignorantly of your position. To me this is simply communicating and sharing prayerful thoughts from one brother to another. You will know your group best -- I know only what you have disclosed about them -- and can prayerfully consider strategies to accommodate their needs as God reveals necessary to you. Otherwise, I will pray for you and your group and that God enables them with humility to understand the importance of the service you are providing them in sharing God's Word.