How is mass conserved in chemical reaction?

i think because in a chemical reaction the same mass of matter must end up in the products as started in the reactants?

"The law of conservation of mass states that the total mass of substances taking part in a chemical reaction is conserved during the reaction."

Mass cannot be created or destroyed in a chemical reaction.  

i guess that visual aids present persuasive examples to what you are presenting, some factors would be theme (does it fit with the color, information, what you are presenting), size (can you see it, is it a big enough span of data/information), and overall look of the visual aid.

hope this : )

double the distance = divide strength by 4