This page shows some more complex combinations to try after you have finished the ones in set one. See if crystals form when you combine more than one different substance in water. Which ones are successful? Which ones are not? Does it make a difference if you change the amounts of any of the different ingredients?
1 cup white sugar 1 cup regular salt 4 cups boiling water
1 cup epsom salt 1 cups table salt 3 cups boiling water
1 cup epsom salt 1 cup regular sugar 3 cups boiling water
Make observations and record your results. I hope you will use this project for ideas for your science experiment.