Limit the number of statements for younger students. If all students end up in either the middle or outside the circle, have them pair up to explain why they agree or disagree. Often there are differences in the justification of their ideas, even if both students agree or disagree with the statement.
Caveats:
Students need to be confident in their thinking when using this strategy. Encourage students to refrain from changing their answer because they see a majority of students move to the inside or outside of the circle.