Density and Convection<span> at the Beach. </span>Convection<span> is heat transfer due to a density differential within a </span>fluid<span>. ... The </span>current<span> begins when the air over the hot sand is heated and begins to </span>rise<span> because of its lowered density. Air from above the ocean is colder and more dense.</span>
Keep the comma
hope that helps
-6-14i you FOIL the form you have to get the standard form