One of the activities I’ve been doing with children this week is making cheese on a campfire, teaching them a little about physical and chemical reactions and using it as a metaphor for how our relationships shape us. Who knew a campfire activity could have this much learning!

The Experiment

To make cheese on a campfire, you will need: 

  • 1 cup of milk
  • lemon juice (use the squirty kind)
  • salt and pepper
  • herbs of choice – we used foraged three-cornered leek
  • crackers or bread

You will also need:

  • a heat source (camp fire, gas stove or hob all work, though campfire adds a smokey flavour to the cheese)
  • a pan
  • sieve
  • muslin or cheese cloth
  • spoon
  • knife
  • mixing bowl
  1. To start with, heat the milk over heat. Keep stirring it so that it does not boil over or burn to the pot. Once it starts boiling, take it off the heat.
  2. Squirt in lemon juice and it should immediately begin to curdle. Once you can see a clear difference between whey and cheese, you can stop adding lemon juice. The amount you need will vary, but a few squirts should do it.
  3. Place the muslin inside the sieve over the bowl and pour the liquid through it.
  4. The whey can be used in stocks, soups etc, but if you don’t want it you can discard it.
  5. Leave the cheese in the cloth for a while to drain. You can also lightly squeeze it.
  6. Mix in salt, pepper or chopped herbs
  7. Spread it on crackers or have a sample on its own.

The Science

In this particular session, we’re looking at physical changes and chemical changes. You can learn a whole lot more about it than I’m going to share here on the Oak Academy (free) lesson on the difference between physical and chemical changes. The short version, however, is that in a physical change, there’s a change in the form or arrangement of a substance. (If ice melts or freezes, it is still water, but the form has changed. If a pane of glass shatters, it is still glass, it has just changed form) In a chemical change, something new is created, and it is very difficult, if not impossible, to change it back to its original form. For example, you can combine ingredients to make a cake. You cannot take that cake and seperate it back into original ingredients – a chemical change has occured. The same applies to making cheese. We can combine our milk and our lemon juice and create cheese – we cannot, however, change back to create milk and lemon juice from the cheese. A chemical change has taken place, and cannot be undone.

The Metaphor

The young people I was working with in this particular session aren’t the type to engage unless they really want to, and they aren’t the kind who’ll sit still and listen for very long. They were curious about how we could make cheese during the session and they couldn’t see how the milk and lemon juice were going to make cheese, so they were willing to observe for a while. This was my opportunity to share a bit of chemistry, but also to impart a little bit of life-learning too – probably the more important bit in this situation. 

As the milk was heating, I explained about chemical and physical changes (see below). I drew the comparison to how, if we’re sad, angry, happy etc those are physical reactions – they change depending on what’s around us. We can go from one emotion to another and back again quite easily.

We then spoke about chemical changes – when we see someone we like we might have a physical reactions – heart racing, pulse quickening, tingly feelings – but they’re all based on a chemical reaction in our brains. I explained to them that every relationship, whether romantic or otherwise, has a lasting impact on who we become. I shared an experience of my own – I was in an abusive relationship for one year, 23 years ago. Even now when my partner, who has never been abusive towards me, becomes agitated, I become uncomfortable, I feel frightened, my body stiffens: it’s a physical reaction to a chemical response (fight or flight) in my brain.

When the milk had boiled and cooled a little, we added lemon juice, and I compared that to the influences around us. It immediately causes the milk to curdle, and even though we don’t taste the lemon in the final product, it has caused a permanent, unfixable change to our milk. It’s important to remember that the cheese isn’t *bad*, and in this case, the change worked out fine, but it was still a change, and one that the milk did not expect until there was nothing that could be done about it.

In the same way, it’s important that we recognise the influences – the lemons – that we allow in our lives, and that we surround ourselves with people that will help us be who and what we might be five, fifteen or thirty-five years from now.

It was encouraging to me that, at the end of our session, I asked one of the lads to recap what we learned about chemical changes today. He didn’t respond with the science, but rather, what had stuck was how our influences change who we become.

The cheese was tasty… the lesson, hopefully life-affirming .


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