`SceneManager' does not contain a definition for `LoadScene'

hi, can someone please help me with this error:

 Assets/Menu.cs(53,22): error CS0117: `SceneManager' does not contain a definition for `LoadScene'

here's my script, thanks.

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 using UnityEngine.SceneManagement;
 
 public class Menu : MonoBehaviour {
 
     public Canvas quitMenu;
     public Canvas instractionsMenu;
     public Button startText;
     public Button exitText;
     public Button instractionsText;
 
     // Use this for initialization
     void Start () 
     
     {
         quitMenu = quitMenu.GetComponent<Canvas> ();
         instractionsMenu = instractionsMenu.GetComponent<Canvas> ();
         startText = startText.GetComponent<Button> ();
         exitText = exitText.GetComponent<Button> ();
         instractionsText = instractionsText.GetComponent<Button> ();
         quitMenu.enabled = false;
         instractionsMenu.enabled = false;
 
     }
 
 
     public void ExitPress()
 
     {
         quitMenu.enabled = true;
         startText.enabled = false;
         exitText.enabled = false;
         instractionsMenu.enabled = false;
         instractionsText.enabled = false;
     }
 
     public void NoPress()
 
     {
         quitMenu.enabled = false;
         startText.enabled = true;
         exitText.enabled = true;
         instractionsMenu.enabled = false;
         instractionsText.enabled = true;
 
     }
 
     public void StartLevel()
 
     {
         SceneManager.LoadScene("1");
     }
 
     public void ExitGame()
 
     {
         Application.Quit ();
     }
 
     public void instractionsPress()
 
     {
         quitMenu.enabled = false;
         startText.enabled = false;
         exitText.enabled = false;
         instractionsMenu.enabled = true;
         instractionsText.enabled = false;
     }
 }