title: Kivy - Slider Class value change on another screen
body: <p>I have a slider which value changes the label. That was easy to understand. Now the problem is I want to use this value to show on another screen. Eventually I want the slider to show 1-16 images on another screen dependent on what value is selected on the slider. Below is what I have as of now, which works well for that screen, but how do I get this value to show on another screen? I know I have to create a class, which have made multiple attempts and each seems to confuse me more than understand it better.  </p>
  
  <pre><code>&lt;NewGameScreen&gt;:
      name: 'newgame'
      BoxLayout:
          orientation: 'vertical'
          height: 100       
  
          Label:
              text: 'New Game'
              font_size: 70
                  Label:
                      text: 'Players'
                      font_size: 30
                      pos: 300, 400
  
                  Slider:
                      id: s1
                      pos: 420, 400
                      width: '250dp'
                      min: 1
                      max: 16
                      step: 1
                      value: 1
                      on_value: s1.value = self.value
  
                  Label:
                      text: '{}'.format(s1.value)
                      font_size: 30
                      pos: 670, 400
  </code></pre>