A brief outline with possible questions:
"Trust in the Lord" What does it mean to trust?
"with all your heart" Sam said this meant to always try your very best.
"and do not lean on your own understanding" This one got an elaborate story from Mom about how sometimes your own understanding can make a lot more sense than trusting in God. A poor man gives away his last loaf of bread to another who has nothing, even though he'll have to go without dinner. Later that day, dinner is brought over from one of his neighbors unexpectedly. God sees the whole picture. Don't believe that what you see is the whole truth. Trust God's truth.
"In all your ways, acknowledge Him" In everything you do, glorify God. Do everything with a servant's heart as working for Jesus.
"And He will make your path straight." Depending on what version you use, the wording here could be a bit different. Some say, "And He will direct your paths." We first asked what they thought that meant. Even if you think your child has no idea, this is always a great way to give them a chance to think it out for themselves. We talked about the promise of heaven to those who follow God's way. Also, when you choose to do God's will and not your own, it is easier to hear His voice directing you in other ways. Your heart is soft to His leading.
Obviously, we try to stick with age-appropriate explanations, but we're usually surprised with how much they grasp, especially Sam, whose spiritual eyes have started to open.
Here's a list of some verses we started with. I think there could be no end to the verse studies we could do even with this small list. The more they are aware of the verses and what the verses mean, the more they will start using the Word to govern their decisions. Like, should I take the biggest cookie, or should I leave it for my brother? Sick and tired of reading that bedtime book they always pick over and over and over? Try some Scripture. It never gets old! (I really didn't mean for that to come off as a commercial!)
Proverbs 3:5-6 “Trust in the Lord with all your heart, and do not lean on your own understanding. In all your ways, acknowledge Him and He will make your path straight.”
Ephesians 6:1 “Children, obey your parents in the Lord, for this is right.”
Psalm 119:11 “Your Word have I hid in my heart that I might not sin against you.”
Ephesians 4:2 “Be completely humble and gentle; be patient, bearing with one another in love.”
Psalm 34:14 “Keep your tongue from evil and your lips from speaking lies.”
Acts 4:32 “All the believers were one in heart and mind. No one claimed that any of his possessions was his own, but they shared everything they had.”
Joshua 1:9 “Have I not commanded you? Be strong and courageous. Do not be terrified; do not be discouraged, for the Lord your God will be with you wherever you go.”
Genesis 1:1 “In the beginning God created the heavens and the earth.”
John 3:16 “For God so loved the world...”
Psalm 18:2 “The Lord is my rock, my fortress and my deliverer; my God is my rock, in whom I take refuge.”
Philippians 4:13 “I can do all things through Him who gives me strength.”