What you’ll need:

  • A bottle of tonic water
  • A little bit of sugar
  • A little bit of salt
  • (Bonus) Blacklight
  • (Bonus) Clear Cup or Glass for the water

Note:  If you are going to do both part 1 and part 2 (bonus) then it may work better to start with part 2 and then do part 1.

Part 1:

  1. Taste some of the tonic water
  2. Discuss the taste
    1. Of the 5 basic flavors (Sweet, sour, salty, bitter, and savory), what do you taste?
      – It should be a bitter flavor
    2. Does anyone know what makes it taste bitter?
      – The bitterness is quinine, a compound derived from bark of the cinchona tree.
  3. Add a little bit of sugar
  4. Discuss the taste
    1. Does it taste sweet or bitter?
      – With just a little sugar it might taste a little sweeter but should still have a bitter taste
  5. This time add a little bit of salt
  6. Discuss the taste
    1. What do you notice in the taste this time?
      –       This time it should taste sweet, like sugar water. Surprisingly, salt suppresses bitterness better than sugar!
      – It’s apparently not known how salt suppresses the bitterness, whether the salt somehow disrupts the bitter receptors on the tongue or whether it’s some sort of post-processing by the brain.

Science learning: This can be a time to learn about the 5 basic types of flavors (Sweet, sour, salty, bitter, and savory)

Spiritual Analogy: Sometimes because of pain or hurts we have experienced, there is bitterness in our hearts.  When we try to be sweet (like adding the sugar) it might help a little but it doesn’t solve the problem.  We need God’s power to eliminate the bitterness.  God has called us to become salt and when we act like salt according to his power, then we can truly forgive and remove the bitterness.

Part 2: (This may actually work better as the first part of the demonstration)

  1. Does the tonic water look different in any way than regular water?
    – Maybe bubbles but nothing else.
  2. Turn off the lights in the room
  3. Turn on the blacklight next to the tonic water (you should see the water glow blue)
  4. What happens to the tonic water in the cup when the black light shines on it?
    – The water glows!

Science learning: This is because the (invisible) ultraviolet light from the black light is absorbed by the quinine in the tonic water, and this excites the quinine. When the quinine becomes unexcited, it releases visible blue light that we see.

Spiritual Analogy: Quinine is the part of the tonic water that is bitter.  Without the blacklight, we aren’t able to see anything significantly different.  But that doesn’t mean there wasn’t any bitterness in the water.  There are times we can have bitterness in our hearts and fool others.  But God knows to to see the truth in our hearts and just like when the blacklight is turned on, God can see that there is bitterness.  We need to be cleansed by God to have the bitterness removed.