A glow stick or a clock with a glowing dial
Previous Preparation: You may need to make the room as dark as possible by covering windows, etc.
With all the lights on have the students read Isaiah 2:5.Turn out the lights and turn on a small lamp and have the students read Matthew 6:22.Turn off the lamp and turn on a flashlight and continuously move the beam around the room and have them read 2 Nephi 10:14.Now turn off the flashlight and activate the glowstick and ask the students to read Doctrine and Covenants 93:26-29.Put away the glow stick and have them try reading anything.
It is more difficult to receive the word of God as the light of truth dims, or our keeping the commandments diminishes.Help the students understand that it is easier to do their work and receive truth when they have all the lights on, or are keeping the commandments.Once we start breaking commandments, then the light gets darker and darker until we are lost completely.Challenge them to think of one or two of their life's darker areas and to set goals to make them brighter.
2 Nephi 10:14