German lerning Alexa skill - How can I solve my users answer understanding and relating problem during the skill

Our project is based on a German learning Alexa skill. The skill is supposed to teach some categorized sentences and words by saying it loud for disabled kids. The kids are the users of the skill. After that the kid should reply by repeating the word or sentence. The response from Alexa should be: ‘very good’ or ‘I can’t understand, please repeat’ or ‘that was wrong you need to say ….

The main problem is that Alexa doesn’t understand the repetition the kid has made. Because if we define many different words as intents or slots, Alexa takes them all as the right answer. But she should only take the correct repetition by the kid of the word she has said before as the right answer.

We thank you already for the help !