Extinguishing fire

This week we carved our 'family' of four pumpkins.  My intention was to have a single pumpkin this year, just like previous years, but unfortunately an online shopping delivery of a 'small' pumpkin that turned out to be about 6cm tall meant I thought we should get another one. The older of my two boys decided that the pumpkins were himself and his brother.  This apparently meant that we needed 'Mummy' and 'Daddy' pumpkin too, so - tempted by very inexpensive pumpkins - we bought two slightly bigger ones too! And thus we had four pumpkins to carve faces into and a lot of scrapings of the inside from which to make pumpkin scones. 

Our 'family' of pumpkins

The boys had more staying power for carving pumpkins than I expected, and we did them all late one afternoon, with the bigger one dictating the facial features and providing odd bursts of assistance in scooping out seeds.  The littlest was mesmerised by the flickering light inside once we'd finished the first one and was happy to watch the rest of the process accompanied by the occasional bashing of the table with a spoon.

We used LED 'tealights' as I knew the pumpkins would get some love from the boys and I didn't want to have to closely supervise the pumpkins or put them out of reach.  However, my son has been curious about candles since his birthday and loves everything to do with fire engines, so I thought it might be a good time to explain a little about fire, and fire safety.

I started off trying to find out what he already knew.  He knew that fires are hot - we have gas hobs and he sees the flames and knows that pans are hot.  He also knew that you could extinguish fires with water, and that this is what fire engines use.  He's even had a go with a real hose at a fire station open day.  He also knew that you could blow out flames on candles.

I got out a real tealight candle, and lit it with a match.  He wanted to check it was hot, so I let him hold his hand above it, and he confirmed it was indeed hot.  I asked whether he could see the light coming from the candle, and we switched the lights off and compared it to our LED candle and saw that it was quite a lot brighter.  We talked about how we sometimes use fire to give us heat (he remembered toasting a marshmallow at a friend's recent outdoor birthday party; he didn't much like the marshmallow but he'd enjoyed the warmth from the fire on an October day), and other times to give us light.

Burning tealight candle

We had a look at the wax, and saw that a little pool around the wick had melted.  I asked if there would be the same amount of wax if the candle kept burning, and he wasn't sure.  I told him we'd check later, but that the fire needs fuel and it gets used up when it burns.  We did check later, and there was less wax than before (I used a new tealight and in the end we burned the candle for around 10 minutes so it was pretty obvious).

Then I asked if the candle needed anything from the air to keep burning.  Again he wasn't sure, so I suggested testing.  I gave him a small glass jar to put over the tealight and helped him put it over carefully.  The flame went out after about 10 seconds.  He thought this was brilliant, and wanted to do it again, so I re-lit the candle!  We talked about what it is in the air that the candle uses up in the jar, and I explained that it's oxygen.  He's aware that oxygen and carbon dioxide exist and are in the air, and also knows that we need to breathe in oxygen from the air; he readily accepted that the candle had run out of oxygen.  He wanted to keep extinguishing the fire, and we did it probably 10 times in the end, I lost count!

Extinguished candle

We talked a bit about how lots of different things would burn, which is why Mummy needed to be careful with the candle so we didn't set anything else on fire or burn ourselves.  I explained how it was important not to play with fire as it could be dangerous if not used correctly.

We had a long walk later in the day, after a spell at the playground with friends (where he was running round pretending to be a fire engine...) and conversation returned to our candle.  I asked whether he thought the candle would stay lit for more or less time if we had used a bigger jar.  He thought it would burn for longer because there would be more oxygen in the jar to use up - he'd clearly understood what we'd done this morning, and when I've got a bigger jam jar to hand we can test his hypothesis and demonstrate that his logic is correct.