Dissolve the Barium Chloride in cold water, cold because the Calcium Sulfate is slightly soluble in water and the cold water will prevent it from being dissolved, then filter out the Calcium Sulfate. More.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.