Objects shortcode inserting anywhere in page – help please.

Hi,

I can create an Object in php register it for a shortcode and inset it in a page.

But i can not figure out how to return data to different places in a paragraph or page.

This is some test code:

class ScTest{
    public function __construct()
    {
        add_shortcode('sc1', array($this, 'shortcode'));
	add_shortcode('sc2', array($this, 'shortcode2'));

	add_filter('widget_text', 'do_shortcode');
    }

// code for sc1
    public function shortcode()
    {
	echo 'not';
    }

// code for sc2
    public function shortcode2()
    {
	echo '1/4/2015';
    }
}

$sct = new ScTest();

Useable short codes are:

[sc1]
[sc2]

I was thinking that if I created a class I could use methods in paragraphs (via shortcode) to say somthing like this:

page
I am a model citizen of planet earth.

with shortcodes

I am a [sc1] model citizen of planet earth.

or:

I am a [sc1] model citizen of planet earth [sc2].

but the page output is:

not1/4/2015
I am a model citizen of planet earth.

I want an output like:
I am a not model citizen of planet earth 1/4/2015.

So can someone point me in the right direction, so I can figure this out?

It would seem that when the page is rendered that the shortcodes are executed first then it renders the paragraph.

Thanks in advanced.
Joe.