Grease a plate or pie dish.
Heat the sugar and golden syrup in a medium-sized pot at a medium-low temperature. Stir constantly with a wooden spoon or a whisk until the sugar has melted.
Simmer on a medium-low heat for 5 minutes, stirring continuously, until it turns a golden amber colour. If you have a candy thermometer, wait until the temperature gets to 145 - 150 degrees C (293 - 303 degrees F).
Take the pot off the heat and immediately add the baking soda. Stir madly and watch it foam up (very exciting for the kids!).
Pour it STRAIGHT AWAY on to the greased plate/dish and leave it to become cold and set. DO NOT TOUCH IT WHEN IT'S HOT (it'll stick to your fingers and burn you).
When it has cooled, break it into pieces and eat it!