React tutorial appears to be broken

The beginners Tic Tac Tutorial produces errors when the code is entered into Codepen.io
There is no way to get Codepen to register the code as correct except when copy pasting the end demo file.
I'm more muddled by the concepts of react after this tutorial rather than informed and practiced by following it.
Rather better way would be to 1) one small module that lets you practice prop passing 2) one small module that lets you define the js code that will use the render method and so forth. The current tutorial seems a stream of thought and as a whole incoherent as a demonstration of reacts strengths.

Inizia riproducendo il Tic Tac Tutorial per principianti in CodePen.io e documenta gli errori che si verificano quando il codice viene inserito progressivamente. Il lavoro è completato quando il tutorial funziona in CodePen e i suoi passaggi supportano chiaramente l’esercizio del passaggio di props e dell’uso del metodo render.