Observation is a very important part of science. It lets us see the results of an experiment, even if they are not the results we expect. It lets us see unexpected things around us that might stimulate our curiosity, leading to new experiments. Even more important than observation is accurate observation. Often, our eyes and our brains play tricks on us, letting us see what we expect to see, instead of what is actually there.
Careful, accurate observation is one of the most important tools for scientists. It is not always easy to do, especially if you are trying to keep your eye on several things at once. That is one of the reasons that scientists work so hard to limit the variables in any testing. If only one thing is changing, it is easier to focus on the changes.
Read this AFTER you have watched the video.
This experiment is a classic trick that science teachers use to teach students about observation. Sometimes we see what we expect to see instead of what is really there. To try this fun trick, you will need:
- a banana with no brown spots
- some slivered almonds or other nuts
- a candle holder
- a lighter
Carefully peel the banana and cut a section about 3 or 4 inches long. You want it to be as straight as possible. You also want to be sure that it has no brown spots. I use one that is still slightly green, as they are firmer and lighter in color. What you are trying for is something that looks like a candle.
Once you have the length of banana, place it into the candle holder. The more fancy the holder, the better the illusion. OK that looks something like a candle, but there is no way we can light the banana on fire. In a real candle, the wick carries melted wax up to feed the flame. A banana does not melt, and even if it could, the liquid would not burn. We need to find a different way to light our edible candle.
For our wick, we will use a sliver of almond. Nuts are rich in oil. Remember that the purpose of the nut is to grow a new plant. The oil is an energy supply for the young plant. We will use the energy in that oil as fuel for our candle. Stick a thin sliver of almond into the top of the banana, so that it looks like a wick. Now your illusion is ready to amaze someone.
Use the lighter to light the top of the almond sliver. It burns with a nice, yellow flame, just as you get from a candle. The big difference is that it will only burn for a minute or so. That means you have to work quickly. Once the candle is burning nicely, carry it carefully into the room where someone is sitting. They will almost certainly ask you why you have a candle. Say that you are hungry and feel like a "light" snack. Blow out the "wick" and bite the top off the candle. Unless your friends and family have seen the trick before, they will probably be amazed.
One thing to be careful of is the hot end of the burned almond. It will cool quickly, but I always make sure I have plenty of saliva (spit) on my tongue to be sure it is completely out. You would not want to burn your tongue.
If someone is very observant, they will notice the difference in the texture of the "candle" and that the wick is stiff and thick. Most people will see what they expect to see, a burning candle. An important part of science is learning to see what is really there, even if it is not what you expect.
Of course, what I expect to see is a bowl of ice cream to go with the banana, and maybe some chocolate sauce, and some nuts, and maybe some whipped cream......
Did you spot all the changes?
00:10 In closeup, I am wearing a different shirt. White buttons instead of brown, and the pockets are different.
00:15 Banana from top of computer is gone.
00:30 As I bite the candle, the lighter on the desk disappears.
00:46 Lighter reappears
01:34 In closeup, the extra bananas have moved onto the cutting board.
01:41 Banana and seashell have appeared in front of the computer. I am wearing a different shirt (the one from the earlier closeup). The tarantula specimen and the crocodile skull have changed places on the shelf. There is a different candle holder, and the lighter and balloon have moved. There is a white paper towel on the side of the table.
02:14 The knife is different. The pieces of banana are in different places.
02:20 The knife has changed back. The picture on the computer screen has changed. The banana has moved onto the shelf by the tarantula specimen.
02:31 In the closeup, the lighter is different.
02:36 The banana is back in front of the computer. The picture on the computer screen has changed back to the original. The lighter is red again.
02:58 The picture on the computer screen slowly begins to change color.