Screens starting on full screen

Question

I’m facing a problem with browsing between screens in my app, the screens are starting on full screen and I can’t leave it normal.

What I call navigation

 void onDonePress() {
    // Do what you want
    Navigator.push(
      context,
      MaterialPageRoute(
          builder: (context) => RegisterUser()),
    );
  }

Screen code that is on full screen

Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        padding: EdgeInsets.all(10.0),
        child: Column(
          children: <Widget>[
          Image.asset(
            'images/logo.jpg',
            height: 200.0,
            width: 180.0,
          ),
          Padding(
            padding: EdgeInsets.only(
                top: 10.0, bottom: 10.0, left: 16.0, right: 16.0),
            child: Text(
              "O que é Lorem Ipsum? Lorem Ipsum é simplesmente uma simulação de texto da indústria tipográfica e de impressos",
              textAlign: TextAlign.center,),
          ),
          Padding(
              padding: EdgeInsets.only(
                  top: 10.0, bottom: 10.0, left: 16.0, right: 16.0),
              child: Column(
                children: <Widget>[
                  TextField(
                    decoration: new InputDecoration(
                      labelText: "CPF",
                      fillColor: Colors.white,
                      border: new OutlineInputBorder(
                        borderRadius: new BorderRadius.circular(25.0),
                        borderSide: new BorderSide(),
                      ),
                      //fillColor: Colors.green
                    ),
                    keyboardType: TextInputType.number,
                  ),
                ],
              )
          ),
          Padding(
            padding: EdgeInsets.only(
                top: 10.0, bottom: 10.0, left: 16.0, right: 16.0),
            child: TextField(
              decoration: new InputDecoration(
                labelText: "Usuario",
                fillColor: Colors.white,
                border: new OutlineInputBorder(
                  borderRadius: new BorderRadius.circular(25.0),
                  borderSide: new BorderSide(),
                ),
                //fillColor: Colors.green
              ),
              keyboardType: TextInputType.number,
            ),
          ),
          Padding(
            padding: EdgeInsets.only(
                top: 10.0, bottom: 10.0, left: 16.0, right: 16.0),
            child: TextField(
              decoration: new InputDecoration(
                labelText: "Tel",
                fillColor: Colors.white,
                border: new OutlineInputBorder(
                  borderRadius: new BorderRadius.circular(25.0),
                  borderSide: new BorderSide(),
                ),
                //fillColor: Colors.green
              ),
              keyboardType: TextInputType.number,
            ),
          ),
          Padding(
            padding: EdgeInsets.only(
                top: 10.0, bottom: 10.0, left: 16.0, right: 16.0),
            child: TextField(
              decoration: new InputDecoration(
                labelText: "Tel",
                fillColor: Colors.white,
                border: new OutlineInputBorder(
                  borderRadius: new BorderRadius.circular(25.0),
                  borderSide: new BorderSide(),
                ),
                //fillColor: Colors.green
              ),
              keyboardType: TextInputType.number,
            ),
          )
          ],
        ),
      ),
    );
  }