Think of the discussion boards like a tennis game - you submit your original post (the serve) and your classmate volleys back to you - a question, a comment, an idea, etc. Your posts should be intended to elicit a return hit, thus keeping the game and discussion going! Discussions should not be static where you return the ball (respond to someone) and never look back. If someone comments on your post, please give them the courtesy of responding back - in the same way you would if you were in a tennis game with that person!
The best discussions happen when there isn’t a single clear answer. Try to uncover different perspectives, ask questions, provide feedback to others, pose new ideas that haven’t yet been explored, or summarize what has been said and add your own perspective. Chase an idea and keep the conversation in play as long as possible! Don’t be afraid to have an opinion that differs from your classmates. It’s okay to respectfully disagree. Remember to explain your reasoning behind your opinions.
And finally, use a casual tone as you would in a conversation. Formal writing isn’t necessary for discussion boards.