Android: pass checkbox status to another activity and use in if statement

In my main activity, I have 6 checkboxes for selecting which parts of a test the person will want to take. I've looked at a bunch of pages trying to figure out what to do, but I couldn't gain a clear understanding of what I was supposed to do.

Let's say, in my main activity, I have the checkboxes:

            CheckBox grade1 = (CheckBox)findViewById(R.id.grade1);
            CheckBox grade2 = (CheckBox)findViewById(R.id.grade2);
            CheckBox grade3 = (CheckBox)findViewById(R.id.grade3);
            CheckBox grade4 = (CheckBox)findViewById(R.id.grade4);
            CheckBox grade5 = (CheckBox)findViewById(R.id.grade5);
            CheckBox grade6 = (CheckBox)findViewById(R.id.grade6);

And if they're checked, I want to pass them to my next activity using this onClick (with whatever code needs to be added to make it work):

private void setupMessageButton() {
    Button messageButton = (Button) findViewById(R.id.main_button);

    messageButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            startActivity(new Intent(MainActivity.this, Test.class));
        }
    });
}

Then in my new activity, I have if statements which are currently written this way:

if (grade1.isChecked()){
      // Do stuff
        }

I'm looking for the simplest way to do this. TL:DR - If a checkbox is checked in one activity, how can I use that status to do something in another activity with an if statement?