Akey and scale are important components in what visual aid

Map--a map needs to key to show what symbols mean and a scale to determine distance. 

Maps commonly have a key or legend to show what different symbols used on the map mean. The scale is used to determine the map distance and transfer that to the real distance. 

Ifound this on google”the munich conference of 1938 was prompted by d. hitler's intention to take control of part of czechoslovakia. hitler sought to unite german-speaking people in a single nation and thus turned his sights on the sudetenland, a german-speaking region of czechoslovakia.” i hope it you