Thread by @IdolScribblings

#ScienceLessonAtHome

Edible Egg Geodes

This will be the last science post until after the easter holidays. So, here is a fun spring-themed crystal growing project.

You will need:

✅A flexible ice tray, cake pop tray or small easter egg mold. (You can use clean half egg shells as molds if you don't have one).
✅ Plain chocolate (about 200g)
✅ Lots of caster sugar
✅ Food colouring
✅ Saucepan
✅ Bowl
✅ Cup

1. Fill your ice tray with water 4 times. Pour this water into a cup and set it to one side.

2. Dry the tray thoroughly.

3. Melt the chocolate. Use the molten chocolate to coat the inside of each cup in the ice tray thoroughly. Before the chocolate sets, sprinkle a little caster sugar evenlt on the inside of each chocolate cup. Set this to one side to cool and set properly.

4. Now put the water we measured out earlier into the saucepan. Warm it up to just below boiling and start adding sugar a tablespoon at a time. Keep adding sugar and stirring until no more will dissolve. You will have to add a surprising amount.

Supervise this step carefully.

5. Remove the pan from the heat and add your food colouring of choice. (For different colour geodes you can just divide the mix and add a different colour to each half).

6. Let the sugar solution cool to room temperature naturally. Do not put it in the fridge. Make sure it is properly cool before the next step.

7. Pour your saturated sugar solution into the cups in your chocolate lined tray. Place it somewhere with an even temperature, where it can sit undisturbed for a few days. Keep your remaining sugar solution safe.

8. After 2 days, tip any remaining liquid out of the tray. You should see that your Geode crystals are starting to grow.
Refill the cups with the remaining sugar solution. (If crystal have stared to form in the solution, zap it in the micro for a few seconds and stirr then cool.)

9. After a further 2 days, tip out any remaining fluid. Leave them overnight to dry thoroughly.

10. Flex your tray to pop out your beautiful sugar geodes.

The Science at Work

Crystalisation happens when:
- Certain molten substances cool and become solid.
- The solvent in a solution evaporates, leaving the solute behind, which crystallises.

Both types are at play here. Chocolate contains microscopic crystals!

Geodes form when a bubble of molten mineral (often calcite or quartz) gets trapped in a surrounding rock. The mineral cools and solidifies incredibly slowly. Large crystals form.

Slow cooling/evaporation makes large crystals. If this happens faster you get smaller crystals.

For different ages:
KS2: Learn the key words solution, solvent, solute and saturated solution. Learn that crystals grow when a molten material solidifies or a solvent evaporates leaving the solute behind.

KS3: Review the above, then learn about Igneous, Metamorphic and Sedimentary rocks. What kind of rocks are geodes found in? Learn about the structure of igneous rocks and how they form.

KS4:
Learn about examples of crystal size being affected by the rate of cooling (eg. Granite v Bassalt).

Research why crystals of different minerals are different shapes.

Research why quartz crystal can be different colours (Rose, Smokey, Amethyst).

Have a good break from the home schooling everyone. I'll be back with more activity ideas after the holidays.