Experimenting with a Candle Flame

– From Dragon to Fire Workshop

by Petra Cohnen

Ergün, my “observational child” for my IHVO-Certificate Course, is now 4;6 years old.
For further reading on Ergün see:
Ergün, 3;10 Years
Ergün and Music
“Peter and the Wolf” and the Fine Arts

He is firmly integrated in the group and has two steady friends: Yves (4;9) and 6-years-old Lisa. He has also made friends with new kids among the pre-school children from another group. Especially Paul (5;3), has become a regular playing mate. The two of them share common interests in dinosaurs and dragons and they both enjoy playing on the exercise track and with the workbench.

Preliminary Considerations / Aims

Over the past few weeks I have been observing Ergün (4;6) and Yves (4;9) playing dragons a lot. They take on the role of the dragons themselves and it is especially important for Ergün that dragons are strong and can spit fire. He often ponders whether dragons ever really existed.

I tell him that I could bring a book about dragons with all kinds of information about dragons. After we have done some research together and he has found out that dragons never really existed but are part of many fairy tales and myths he and Yves come up with a whole lot of dragon stories themselves. In every one of them fire spitting is an important part of the plot.
A mind map I create together with the two boys on the topic of “dragons” (see also: Plans, Drawings, Sketches, Mind-Maps) substantiates my notion: aside from the aspect of “dragons and dinosaurs compared” the topic “fire” is the most thrilling one. Ergün and Yves talk about the dangers of dragons spitting fire, of objects / people burning, how a fire can be extinguished and so forth, and they have a great many questions about all this.

I realize that while Ergün and Yves show major interest in this, they have little factual knowledge. (“What to use to put out a fire?” / “What burns, what doesn’t?”)

Since I have seen Paul show interest in the topic “fire” too, I decide to get him involved in our activities. Ergün himself has been showing sustained interest in the topic, so it seems to be just the right time now.
I am going to do some experiments on the topic of “fire” with Ergün, Yves and Paul:

• •  lighting a candle with a match
  •  extinguishing the flame by blowing it out
  •  extinguishing the flame by depriving it of oxygen (put a glass over the candle)
  •  flammable and non-flammable materials

It will be crucial which further questions the children come up with. If they should ask questions I cannot answer right of the top of my head I will discuss possible explanations with them and then promise to bring back the information to our next session. I will make it a point to also demonstrate what I did to get the information.

The children and I are going to compile the documentation of our experiments and their results in a workshop diary.

Since Ergün has been showing interest in letters for quite a while, I assume he will want to lay down some of our findings in the workshop diary in writing. The other two children have shown interest in letters but not in writing. Their interest in writing will either be aroused by these activities or Yves and Paul are going to draw the pictures to go with the texts. This effort will be of equal importance as is writing things down, since the majority of our children cannot read yet.

If along the way their focus should shift to other topics or aspects I will go with it and prepare appropriate experiments. Such related topics might be: air and oxygen / water / letterpress printing and the making of books.
At the end of the project the workshop diary and the experiments are to be presented to the children.

Technical Analysis:

Lighting a match:

The match head of contemporary matches is made of potassium chlorate, a salt which contains oxygen and serves as a fire accelerant. The striking surface on the side of the matchbox contains red phosphorus which is easily flammable.

When the match head is rubbed against the striking surface on the box the two easily flammable materials come into contact. The frictional heat so created is enough to ignite the mixture of potassium chlorate and red phosphorus.
The wooden sticks are soaked with paraffin which burns better than wood. This helps keeping the flame going.

Lighting a candle:

Candles are mostly made of paraffin or other artificial waxes which burn easily and melt at temperatures of 60°C and up. Upon further heating the liquid wax will become gaseous and spread as vapour. When the wick of the candle is ignited the wax near the wick melts from the heat. The wick is made of cotton threads with tiny spaces between them forming tubes/canals.
Liquids show a peculiar behaviour (so does liquid wax): They ascend in narrow tubes, this is called ‘capillary action’. The liquid wax ascends through the gaps in the wick, and getting close enough to the flame it becomes gaseous. Now it can be burned in the candle flame while new liquid wax is being sucked up through the wick, as if in an elevator.

The burning of the flame releases energy in the form of heat and light while smoke, grime and ashes are created.

Extinguishing a Candle Flame by Blowing it Out:

The blown air cools the flame down so that it drops below the flash point (see further below) which is necessary for burning.

Extinguishing a Flame by Depriving It of Oxygen:

If the flame is no longer being fed with air, for example by covering the flame, it will quickly extinguish as soon as there is not enough air/oxygen left to keep the flame alight.
Flammable and Non-Flammable Materials:

The essential characteristic of a flammable material is its ability to react with oxygen and emit heat and light in the process. In the burning process oxygen is being bonded. Materials which allow for this chemical reaction are flammable, all others are not. How easily a material will burn is dependent on its autoignition point and the flash point.

The autoignition point (also and confusingly called flash point) is the temperature to which a material (solid, liquid, steam or gas) must be heated to ignite exclusively because of its own temperature – without an external source of ignition.
When, for example, a match is struck at the striking surface of a matchbox the autoignition point of phosphorous must be reached. It is at 300° C.
The flash point of a material is the lowest temperature at which it can vaporize to form an ignitable mixture in the air. The burning process will normally cease after a short while after ignition if the temperature of the flash point is not reached. This happens if no sufficient amounts of flammable vapours are being created to keep the flame alight. The candle would in this case go out.
The wax of the candle has a flash point so low that the ignition will heat up the wick, and the wax close to it, sufficiently to keep the candle burning after ignition. The flash point of candle wax (paraffin) is at 200°C.

Aims of the Activities

• • Ergün, Yves and Paul gain new insights on the topic of “fire” and on further topics arising from the questions the children ask.
  • By making experiments they learn to express their hypotheses about the result, then to compare these with their actual findings and identify possible causes. This promotes their systematic thinking, their deductive reasoning and an explorative attitude.
  • Ergün, Yves and Paul experience their questions as being welcome and their interest and curiosity being appreciated if not even causing my awe. Through my attitude they are to experience their questions as something positive and this should encourage them.
  • Ergün practises writing letters and using the table of initial sounds. Yves and Paul are to be inspired by this and maybe even make their own first attempts to write.
  • The children experience how their questions determine the further course of experiments and activities to a large degree. Paul and Yves experience themselves as competent and knowledgeable as they pass their expertise on to other children and arouse their interest.

Realisation

For the first experiment I have set up: a candle, matches, a plate for the burnt matches, three empty water glasses of different size and some water for safety reasons. Yves and Paul call some of the things by name, Ergün knows the terms striking surface, wax, wick and match head. Upon my question about the function of the parts he explains: “When the candle is burning the wick is on fire and the wax becomes wet.”

I inquire whether the wax really becomes “wet” when the candle is burning and the three boys start reasoning. Paul doubts it but does not have an alternative explanation. I ask: “What happens if the water gets really close to fire?” “The fire goes out”, says Ergün without missing a beat.
To support his statement I ask Ergün whether he would like to light the candle and then pour some water next to the wick. He does and I notice how skilfully he handles matches. He tells us that he has practised this at home with his father on quite e few occasions. The flame ceases as expected and Ergün’s hypothesis is confirmed. “See, like I said”, he says. Everybody understands that what can be seen close to the wick cannot be water.

The children cannot find the answer and I do not want to give it away so we decide to come back to it later. Meanwhile I ask the children to keep the question in mind and to closely watch the wax later when the candle is burning.

I ask the children what else is planned for today’s experiment. Paul and Yves think that each of us is going to light the candle and then extinguish it with water. I confirm their guess, telling them that we are going to check how to extinguish a candle with water and that this is one way of putting out a flame. They both want to do it themselves and they do so one after another. On each go I ask the two other boys, who are standing by, to watch the process with great attention. They discover: The flame goes out every time the water touches the wick.

Ergün notices something: “When Paul held the match to the wick after it was put out with water there was a hiss!” I ask him what he thinks might be the reason for that. “It’s the water, it gets hot”, says Ergün and everybody else agrees.
I confirm their hypothesis and give them the following explanation: There is extinguishing water enclosed in tiny pockets in the wick. The heat from the flame of the match vaporises it. The steam so created needs more space than liquid water and so it bursts out. That is the “hiss”.

Now I ask the children whether they can imagine any other ways of putting out a candle flame. Ergün says the candle could be blown out too, which Yves and Paul confirm. Everyone lights the candle and tries to put it out by blowing. Yves and Paul are making progress getting the match lit by striking at the right angle and with the right speed. Ergün is eager to help them when asked. I watch him doing a great job in helping them and I observe the scene, with no need to interfere.

The children do not ask why the candle flame goes out when blowing against it. I just leave it at that since I want to go along with the questions the children ask.
Presently they are interested in what the matchstick consists of.

We talk about the appearance and the function of the matchstick. The term “red phosphorous” is not known to the children, but it seems to fascinate them, they use the term several times and correct each other as to its use.

The frictional heat is discovered by Paul when he sweeps his finger over the striking surface after several tries, finding that it feels warm now.
It is Ergün who notices the smoke going up after the flame has been extinguished. He holds his nose and says: “That stinks”. We talk about the smoke and Ergün explains that the smoke is not good for our health, it makes a person cough. I agree and upon his suggestion we open the window.

I ask the children when it was that they discovered the smoke and if they have any idea what smoke is. Yves describes the colour of the smoke as being dark and Ergün has observed that smoke went up when the candle was blown out. “And then it was gone”, says Paul. “But not all of it”, says Ergün, “I can still smell it.”
I pick up Ergün’s statement and explain to them that the smoke, which had gone up after the candle had been blown out, comes from unburned wax particles. When the flame goes out there is no more wax vapour ascending through the wick, so the wick itself burns up a little until it has cooled off.

Ergün wants to know how the tiny wax particles get into the wick. I ask him and the other two children to take a closer look at the wick where it comes out of the candle. The candle has been burning for a while at this point and the wax is liquid.
I realise that this is a good time to get back to the question of whether the flame makes the wax wet and to clarify it.

Ergün states that there is a liquid at the bottom of the wick, everybody agrees that this must be wax. Paul says: “The flame is hot and melts the wax.” Ergün and Yves come to the same conclusion. To verify it they want to light a tea candle and see if there too the wax becomes liquid. The test shows the same result which settles the question for the children. Ergün makes the remark that liquid wax and water look very much alike. “That’s why I thought it was water”, says Ergün.

I want to make sure that the children understand why that liquid cannot be water and ask them about it. “Well, because water would make the candle go out and this one here (points at the candle) keeps burning even though there is liquid there”, says Ergün.

Now I explain to the children that wax consists of hydrocarbon. When wax is solid the hydrocarbon particles are bound together, by heating the wax the particles lose their bond and become more “mobile”, separate and eventually begin to flow. The wax becomes liquid. Theses “particles” are so small and mobile that they can move up through the wick and burn.

I am thrilled by his astonishment and I tell him so: “Yes, right? It’s just marvellous and one can hardly imagine it”, I say. Ergün concludes: “Now I know why the candle gets smaller when it burns for a long time: first the wax becomes liquid, then it goes through the wick and then it gets burned and goes up in smoke.”

For today we are finished with our experiments and we discuss how we are going to document our findings in our workshop diary. We decide to start working on the diary at our next session.
Ergün declares that he definitely wants to do the writing. He notices that we never got around to using the three glasses. I tell them that we can do that at the next session and I ask the children to give it some thought in the meantime and figure out what they might be used for.

Workshop Diary

At the beginning of our next session we start working on the diary. Ergün has many questions and definite ideas as to what the diary should look like: “A real book has a cover in front and in the back, do you have something like that, Ms Cohnen? And it has to be fixed on the side not just with staples.” We discuss what materials we have at our disposal. Hard cardboard for the cover and a coil binding machine are available and Ergün is happy.

Together we review our findings from last time; Paul, Yves and Ergün remember almost all results and experiments, the only thing they have forgotten is the term hydrocarbon, they circumscribe it with the phrase “very small particles”.

We decide who gets to describe which result and how he goes about it. Ergün is using the initial sound table. Paul hesitates but eventually uses one too and begins to work. After a short while I notice that he is having trouble and has quit working. He seems sad but he is not saying anything. I ask him whether it makes him sad that he is not able to work with the initial sound table. He nods and accepts when I offer my help.

I help him by having him pronounce the word he wants to write very clearly. Together we then figure out the letters of the word “candle”, he then looks up the characters one by one and writes them down on his sheet. At the end he is quite proud of having written a word himself. But it is also clear now, that he still has great difficulty with writing and that it takes up a lot of time for him.

Ergün cannot quite understand that Paul – who is about to be enrolled at school – does not like writing. It makes more sense to him when I tell him that this was Paul’s first attempt to write. “Yes, I have been writing at home for a long time and I have much more practice”, he says. Paul, being the older one of the two, is relieved by my explanation and says: “When I feel like it I can now write a bit.”

The two agree to finish Pauls sentence about the candle together.
Yves makes a drawing of the smoke going up over the candle. His drawing is quite detailed and he says: “This way everybody can see exactly how it works with the smoke.” I tell the boys how well they have done and how pleased I am with the fact that they have already found out and learned so much about the topic fire.

Extinguishing the Candle by Depriving It of Air

After this part of the work on the workshop diary has been finished I again set up a candle, a plate for the burnt matches, three empty glasses and some water for safety.
I ask the children whether they have any idea what the glasses and the candle are for. Nobody answers and I say: “Imagine you want to put out the candle. You don’t have any water and your mouth is full of candy so you don’t want to blow it out. What else can you do, using the things on the table, to put out the candle?”

Ergün takes one of the glasses and says: “I can put it down over the candle”. I encourage the children to speculate what would happen if Ergün used the glass the way he described and why this was so.

Paul thinks the candle keeps burning and the glass gets very hot. Yves apparently remembers the melting wax and says: “The wax is going to melt and touch the side of the glass”. Ergün says: “The glass gets hot and the candle goes out”.

We do the experiment. Each child tries with a different size glass. We keep track of the results. It soon becomes clear that the candle always goes out and that it takes longer the bigger the glass is.

The true cause, however, is not understood before I tell the children that the flame needs something that is in the room and therefore also in the glass. But there is only a little bit of it in the glass, and when this tiny amount is used up the flame cannot burn any more. “Air!”, shouts Ergün, Paul and Yves agree.

I tell them that the part of the air needed by the flame is the oxygen. “Yes”, says Ergün, “we need it to breathe too, it goes in our lungs”. This triggers an exchange about diving, holding one’s breath, getting no air.

Now Ergün wants to determine exactly how much longer the flame burns under the big glass as opposed to the smallest glass. I ask him if he has an idea how this could be done. Paul says we could do a countdown. Ergün spots a clock with a sweep hand and we agree to count the seconds.

With the smallest glass (a shot glass) it is hardly 2 seconds, the next bigger one lets the flame go on for about 8 seconds and under the biggest glass the flame lasts 12 seconds, then the oxygen is used up. At the next session we document these findings in the workshop diary too.

The following experiments about flammable and non-flammable materials took a similar course. The children tried stone, sand, iron nails (do not burn) and paper, wood and cardboard (do burn).
During these experiments, too, Ergün, Yves and Paul observed closely and drew good conclusions.

Ergün was also quite interested in the topic “grime”. He discovered the creation of grime in the burning process of a candle and wanted to try out if he would write with that grime. I told him about cave paintings of Stone Age man. He found that very interesting and the three of them looked at pictures of cave paintings.
In the course of the following experiments the children mixed grime with water and made their own cave paintings.

They were also very interested to know how large fires can be extinguished. Different possibilities were considered. Even though I had not planned it we spontaneously tried extinguishing with sand, since Ergün had found out that sand does not burn. We deliberated how, for instance, a campfire could be put out and Ergün remembered sand. So we found a suitable spot outside and tried the extinguishing properties of sand.

Of course the boys also mentioned the fat water hoses fire fighters use. Yves told a story of a fire fighter operation and the huge amounts of water coming out of the hoses. Ergün asked the continuative question: “And where does the fire department get all that water?” A lively discussion developed among the children in the course of which I explained the term “fire hydrant” and the signs pointing to them in the streets. Ergün’s, Paul’s and Yves’ next object was to find out more about fire hydrants.

Reflexion

I think I have achieved most of my objectives. Ergün, Yves and Paul have acquired new knowledge on the topic of “fire” and another topic was found on the way, which they want to find out more about (fire hydrants).
Each one of the boys asked questions, gained insights and drew conclusions in accordance with their individual state of development.

Once more I have seen how Ergün is way ahead of his peers in age when it comes to verbal skills and cognition. His power of observation often led him to identify interrelations the other two boys did not see. (Examples: the creation of smoke, grime, burning process of wax.)
Comment by the course instructor:
The small group was put together well; even though Ergün, being the youngest among them, still showed the most advanced and most creative thinking, the two were able to keep up pretty well and contribute, if less so than he, their own ideas and considerations. With children of lesser motivation and aptitude a harmonious and successful collaboration with Ergün might not have been possible.

Ergün often took on the active part, it was he who was able to name things and facts and contribute new thoughts. He showed a cooperative attitude and willingness to collaborate (finish a sentence together with Paul). And he was able to put himself in Paul’s position when he had trouble writing.

He immediately communicated his newly acquired knowledge to the other children and at home. He told his parents at home about cave paintings, how grime was created and which tiny particles were contained in smoke. He learned technical terms like hydrocarbon and red phosphorous and he can provide rudimentary explanations of their meanings.

I think the activities were right for Ergün, with respect to topics and timing. He showed sustained interest and perseverance. Our sessions usually lasted for about one hour; directly afterwards Ergün sometimes wanted to keep working on the workshop diary and – as he phrased it – “write some more in peace and quiet”.

Yet there were also days on which he was not concentrated, where he did want to do some writing but had to accept that it was not going so well. On such days he needed my encouragement. I would tell him that it was perfectly OK if he wanted to finish some other day and gave it a thought and see if there was not something else he would like to do instead at that moment. In most instances he decided that he would continue drawing pictures for the workshop diary.

Ergün’s group kept receiving new information from him on the topic of “fire”. In addition the children from our entire kindergarten profited from the research done when the workshop diary was presented and the experiments were conducted in front of all them.

My attitude and the input I gave provided for a setting which invited Paul, Ergün and Yves do do some scientific thinking and at the same time feel safe in moments of insecurity (for example when Paul had trouble using the initial sound table or our talks about the dangers that come with fire).

After its completion, Ergün, Paul and Yves presented the workshop diary on the topic of “fire” to the four groups of our kindergarten separately. During these presentations the three boys conducted some of our experiments all on their own. And they did a good job passing on their knowledge to the other children. They asked questions, took the children’s suggestions seriously and encouraged them to do their own thinking.

Ergün: “Think about it, do you have any idea why the wick isn’t burning any more?” I was really excited to hear how much of their newly acquired knowledge they had memorized and how they were able to convey it to others. The consistently positive reactions by my colleagues were also a great joy for me. They were thrilled by the self-confidence and pride with which Ergün, Yves and Paul had presented their insights.

Ergün, for instance, noticed the difference between burning and smouldering when dealing with the question of flammable and non-flammable materials.
I feel my approach of leaving plenty of freedom to the children to decide how they want to proceed will continue to be fruitful.

Further Ideas

Together with other children I conducted a series of experiments on the topic of “air/flying”. Here too, I prepared the activities according to the principles described above. These activities resulted in a “topic box” with all the materials and manuals to lead through the experiments.
This box is now stored in our library for all other colleagues to use. Another topic box labelled ”fire” is currently in the making.

I hope many of my colleagues will be impressed enough by Ergün’s, Paul’s and Yves’ accounts that they too are going to offer activities of the kind. I will be talking about our activities with great enthusiasm and I am sure so will Ergün, Paul and Yves.

Suchbegriffe in Wikipedia:       Search keywords in Wikipedia:
Streichholz                                   match
Wachs                                          wax
Lipide                                           lipid
Brennbarkeit                                flammability
Flammpunkt                                 flash point
Zündtemperatur                           ignition temperature
Fettalkohole                                 fatty alcohols

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Date of publication in German: 2013, December
Copyright ©  Petra Cohnen, see Imprint.