Tests were conducted at secondary school level on the introduction and application of different languages. Their choice was governed both by the kind of application intended and by different educational aims in turn dependant upon specific curricula. The benefits and drawbacks to beginners by the introduction of different languages in their early upper secondary school years (ages 14-16) is reviewed. On the basis of classroom experiments to compare procedural languages, Pascal in particular, with the more recent declarative ones, such as Prolog, the problems raised by their introduction as well as their educational applications are discussed.