A Smothered Candle

Theme: The gospel must be shared.

Bible Verse: Nor do they light a lamp and put it under a basket, but on a lampstand, and it gives light to all who are in the house. (Matthew 5:15)

Materials Needed:

• Votive candle

• Lighter

• Large clear bottle or glass

• Shallow bowl

• Water

• Food coloring

Bible Lesson

In our early Sunday school years we sing

This little light of mine,

I’m going to let it shine . . .

Hide it under a bushel, no!

This light pictures our new life in Christ. If we truly comprehend what he has done for us, we will be compelled to share Christ with others. How can such exciting, life-changing news be kept under cover? The term basket in our key verse refers to a dry measure of volume, about one peck in Bible times, or one quarter the size of a modern bushel basket.

Matthew 5:16 goes on to acknowledge the good deeds that result from a Christ-centered life. The verse teaches that hiding one’s Christian light either under a bushel or behind a closed door is selfish. After all, any praise that others give for our good deeds belongs to God, not to us.

Science Activity

Place the lighted candle in the shallow container. It should be partially submerged in water. The depth of water is unimportant, as long as the glass will easily fit over the candle and down into the water. The candle burns brightly while in the open.

Next, put the glass in place over the candle and down into the water. Several interesting things will happen quickly. The candle will continue burning for a few seconds. It will also heat the air inside the glass, causing large gas bubbles to leave the bottom of the glass. Then the candle will go out as it exhausts its oxygen supply. The air remaining inside the glass then cools and contracts, pulling water back up into the glass. The rising water level is more easily seen if a small amount of food coloring has been added to the water.

The candle burns fine as long as it is in the open air. However, when sealed up inside the glass without oxygen, the flame cannot continue burning. Likewise, the Christian life is not designed to be sealed up and kept a secret. The Good News is meant to be shared with others.

A candle trapped under a glass cannot continue burning.

Science Explanation

This experiment is often explained incorrectly. The burning candle is said to use up all the oxygen, resulting in a vacuum that pulls the water upward into the glass. This is incorrect. The oxygen gas is converted to an equal amount of carbon dioxide gas, not a vacuum. As the candle goes out from lack of oxygen, it is the cooling, contracting air which then causes a partial vacuum inside the glass. A simple combustion reaction can be written for the candle involving carbon, C, oxygen, O2, and the resulting carbon dioxide, CO2:

C + O2 → CO2

When the air initially expands by heating, its volume change is proportional to the temperature increase. If the air inside the glass doubles in temperature, then a glassful of air escapes in the initial bubbling process. When the candle is extinguished, the remaining air likewise cools and contracts. It is quite surprising how high the water level rises inside the glass.