Enter a specific word script

Hi!

I want to make it so that when it pops up a message on the screen at a set time or something
the player has to write it, I don't know what it's called but you get my drift, I was thinking something like:

var testMaterials : Material[];

 var tOn : boolean;
 var eOn : boolean;
 var sOn : boolean;
 var tOn2 : boolean;
 
 function Start() {
     renderer.sharedMaterial = materials[0];
     var tOn = true;
     var eOn = false;
     var sOn = false;
     var tOn2 = false;
 }
 
 function Update() {
     if(tOn && Input.GetKeyDown(KeyCode.T)) {
         renderer.sharedMaterial = materials[1];
         eOn = true;
         tOn = false;
     }
     if(eOn && Input.GetKeyDown(KeyCode.E)) {
         renderer.sharedMaterial = materials[2];
         sOn = true;
         eOn = false
     }
     //... and so on
 }

You see where I'm going with this, I want it to change material or
something like that so the text highlights or the letters I have entered
highlights/changes color. This is an awful way to do it, so if you have any suggestions
to other ways of doing it, that would be great :)