The "Sand, Pebble, Rock" Stewardship Demonstration
The "Sand, Pebble, Rock" demonstration has been around for a long time. It is often used in a secular way to demonstrate how we can manage our time. It has also been used to visually demonstrate organizing your priorities.
There are several versions on YouTube. The following is a children's sermon version.
Main Point: Stewardship of priorities -- making sure you're taking care of the most important things first.
Lesson Suggestion: After you do the basic demonstration, read Matthew 6:33 "Seek first," and ask "What are "the most important" things?" Suggest that the students decide what some of the big rocks are, write on them. Then invite pairs of students to do the demonstration themselves as you videorecord them with your cellphone.
Scripture: "Seek First the Kingdom of God, and then all these (other) things are possible. Matthew 6:33
One negative is that the visual suggests you can "have it all," when in fact, there are things we that do and want that we should probably NOT do and want. I think the metaphor and demonstration could be adjusted to force students to consider "which things" they need to STOP making a priority, or filling up the space of the lives with.
"Empty" Space is also not a bad thing, rest, contemplation, etc. You could represent that by using clear glass marbles (or by simply NOT filling the jar to the top). In fact, you could use various types of colored rocks to represent different categories.
Playing with the metaphor is something older kids, youth and adults can easily grapple with. For younger children, keep the metaphor simple and make sure they understand what the various rocks represent.