Sec. 3. PLAN AND MAP. Before undertaking to create, revise or rearrange the boundaries or to change the territory in any school district, the County Board of Education shall cause a plan and a map to be made showing the boundaries of all districts affected and of the new districts, if any to be created, with the area, taxable wealth and scholastic population of such districts so affected or to be created, and before such action is taken, all interested persons shall be given an opportunity to be heard.