Image: Mario Sarto @ wikimedia commons

The story

I have been busy in the kitchen for the past few weeks trying to perfect the technique for growing edible sugar ‘diamonds’ and I think I’ve just about cracked it. This is so I can share an activity with you for your KS2 or KS3 science classes that is related to the Queen’s diamond jubilee – the things I do in the name of science!

This is a gem of an activity (sorry!) that you could do as a fun lesson on the last day before the half-term break or you could give it to your students to complete as a homework over the holidays. All the equipment needed for the experiment you can easily find at home.

Top tips:

  • Use a string with a rough surface. I have been using necklace string from my daughter’s bead kit and it’s a bit slippery for the sugar crystals to adhere to.
  • Keep your solution out of the sunlight. I had my first attempt on a bright window sill and was wondering why no crystals were forming. I think the changes in temperature were causing the crystals to keep dissolving back into solution. My second batch I kept in the cupboard and did much better. Here is a photo of the necklace after about 3 weeks.

Teaching resources

I have written two PowerPoints for this: a KS2 version and one for KS3. You can either display the steps as they carry out the experiment in class or you could print them out as a handout for them to take home. As this is related to a topic on solutions I have added some questions to the end. The ones for KS3 ask the students to use the particle model to explain dissolving. I found a great flash animation on The National STEM Centre website that you are free to download and add into the presentation which will help them to visualise this (link below).

KS2 version                                                                               KS3 version

Other teaching ideas to use with the practical:

  • Ask the students to predict what will happen to the mass and volume of the water as sugar is dissolved. They could plan how to do this and carry it out. They will probably predict correctly that the mass will increase but may think the volume will stay the same (it increases). Can they use the particle model to explain these observations?
  • Get them to research more into the process of crystallisation.
  • Classify the formation of sugar crystals as a physical change or chemical reaction.
  • Use the solubility graph (displayed right, click to enlarge. Also on the KS3 PowerPoint) to ask students to work out the maximum mass of sugar that they will be able to dissolve into their water (they will need to use a thermometer to measure the temperature of the water). Discuss with them why it would be a good idea to keep the water as hot as possible throughout the experiment.

As this is my last post this half term may I take this opportunity to wish you a restful holiday and hope you enjoy the jubilee weekend, whatever you are doing (even if it’s not making edible diamonds – it should be though)

Weblink

Rate of dissolving resources from The National Stem Centre. The flash animation ‘dissolving – a closer look’ shows how dissolving happens using the particle model. You will have to sign up to the website in order to view it but I recommend you do as is has a wealth of useful resources.

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