"Field " " is never assigned to, and will always have it's default value null"

Hi im 100% new to coding I was following this tutorial for a quiz https://www.youtube.com/watch?v=zLnnpUsxu0U and I'm done but it keeps giving me this warning in monodevelop "Field "__ " is never assigned to, and will always have it's default value null. the problem is

 [SerializeField]
 private Text factText; 
 to 
 [SerializeField]
 private Animator animator;

heres the code (c#)

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using UnityEngine.SceneManagement;
 
 public class GameManager1 : MonoBehaviour {
     public Questions[] questions;
     private static List<Questions> unansweredQuestions;
 
     private Questions currentQuestion;
 
     [SerializeField]
     private Text factText;
 
     [SerializeField]
     private Text trueAnswerText;
     [SerializeField]
     private Text falseAnswerText;
 
     [SerializeField]
     private Animator animator;
 
     [SerializeField]
     private float timeBetweenQuestions = 1f;
 
     void start ()
     {
         if (unansweredQuestions == null || unansweredQuestions.Count == 0)
         {
             unansweredQuestions = questions.ToList<Questions>();
         }
 
         SetCurrentQuestion();
     }
 
     void SetCurrentQuestion ()
     {
         int randomQuestionIndex = Random.Range(0, unansweredQuestions.Count);
         currentQuestion = unansweredQuestions[randomQuestionIndex];
 
         factText.text = currentQuestion.fact;
 
         if (currentQuestion.isTrue)
         {
             trueAnswerText.text = "CORRECT";
             falseAnswerText.text = "WRONG";
         } else
         {
             trueAnswerText.text = "WRONG";
             falseAnswerText.text = "CORRECT";
         }
     }
         
     IEnumerator TransitionToNextQuestion ()
     {
         unansweredQuestions.Remove(currentQuestion);
 
         yield return new WaitForSeconds(timeBetweenQuestions);
 
         SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
     }
 
     public void UserSelectTrue ()
     {
         animator.SetTrigger("True");
         if (currentQuestion.isTrue)
         {
             Debug.Log("CORRECT!");
         } else
         {
             Debug.Log("WRONG!");
         }
 
         StartCoroutine(TransitionToNextQuestion());
     }