I found this handout which includes useful language for debating for ESL students: https://www.teflsites.com/Expressions%20for%20Discussion%20and%20Debate%20new.pdf
In order to make this huge list more manageable, I selected some of this language that I could put on one sheet (double-sided) to print out and give to my students.
My document: docs, pub.

I'm indexing this with my material on debating practice, and with my general TESOL material.  

Expressions and Topics for Agreeing and Disagreeing

(TESOL Worksheets--Speaking, Debating)

Google: drive, docs, pub
[Found this in my archives the other day.  It's from 3 years ago.  I don't remember why I never posted it at the time.  It looks like this was modified from a worksheet a colleague had made, and I probably didn't view it as my own original work, so I never posted it at the time.  But looking at it now, I'm fairly sure that I put a lot of work into modifying this and adding to this.  So I'm going to claim it as one of my own.]

Expressions for Agreeing and Disagreeing

Stating an opinion	In my opinion... The way I see it... If you want my honest opinion.... According to Lisa... As far as I'm concerned... If you ask me...
Asking for an opinon	What's your idea? What are your thoughts on all of this? How do you feel about that? Do you have anything to say about this? What do you think? Do you agree? Wouldn't you say?
Expressing agreement	I agree with you 100 percent. I couldn't agree with you more. That's so true. That's for sure. (slang) Tell me about it! You're absolutely right. Absolutely. That's exactly how I feel. Exactly. I'm afraid I agree with James. I have to side with Dad on this one. No doubt about it. (agree with negative statement) Me neither. (weak) I suppose so./I guess so. You have a point there. I was just going to say that.
Expressing disagreement	I don't think so. (strong) No way. I'm afraid I disagree. (strong) I totally disagree. I beg to differ. (strong) I'd say the exact opposite. Not necessarily. That's not always true. That's not always the case. No, I'm not so sure about that.
Interruptions	Can I add something here? Is it okay if I jump in for a second? If I might add something... Can I throw my two cents in? Sorry to interrupt, but... (after accidentally interrupting someone) Sorry, go ahead. OR Sorry, you were saying... (after being interrupted) You didn't let me finish.
Settling an argument	Let's just move on, shall we? Let's drop it. I think we're going to have to agree to disagree. (sarcastic) Whatever you say./If you say so.

Topics for Debate

Here are 20 topics to discuss with a friend or group. Practise agreeing and disagreeing even if you have to argue against something you actually believe in. One way to have fun with this is to make up a bunch of cards that say agree or disagree. Each person has to pick up a card and then the topic is read out. It is more fun to have a debate this way because you don't have to play your true self. Try to continue each discussion for at least five minutes. Use the expressions that you learned, including agreeing, disagreeing, asking for opinions, interrupting, etc.

• Breakfast is the most important meal of the day.
• Swimming in the ocean is better than swimming in a public pool.
• Alcohol should be illegal.
• Children should provide room and board for their ageing parents.
• Studying grammar is more important than practising conversation skills.
• Television is the leading cause of violence in today's society.
• Dogs make better companions than cats.
• Smoking should be permitted in public places.
• Females are better students than males.
• A parent shouldn't pierce a baby's ears.
• Lawyers should make a higher salary than nurses.
• Reading English is more difficult than listening to English.
• Summer is the best season of the year.
• Children under 13 should not be allowed to babysit.
• High school students should wear uniforms.
• 21 should be the legal driving age around the world.
• Classical music is the best kind of music.
• The government should pay for post secondary education (i.e. university education).

Breakfast is the most important meal of the day.	Swimming in the ocean is better than swimming in a public pool.	Alcohol should be illegal.	Children should provide room and board for their ageing parents.	Children should provide room and board for their ageing parents.
Studying grammar is more important than practising conversation skills.	Television is the leading cause of violence in today's society.	Dogs make better companions than cats.	Smoking should be permitted in public places.	Females are better students than males.
A parent shouldn't pierce a baby's ears.	Lawyers should make a higher salary than nurses.	Reading English is more difficult than listening to English.	Summer is the best season of the year.	Children under 13 should not be allowed to babysit.
High school students should wear uniforms.	21 should be the legal driving age around the world.	Classical music is the best kind of music.	The government should pay for post secondary education (i.e. university education).

agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree
agree	disagree	agree	disagree

Blank cards for student’s own topics

Agreement or Disagreement: Discussion Questions

(TESOL Worksheets--Speaking, Market Leader: Intermediate, Debating)

Google: docs, pub
These are a list of discussion questions for students to talk about in groups of 3.  The idea is that in the course of the discussion, they use some phrases for agreement and disagreement.
I designed these cards to supplement p. 11 of Market Leader: Intermediate textbook, Skills: Taking Part in Meetings.  For that reason, all of the discussion questions assume an office environment as the setting.
But I think this could also be used as a general speaking activity, independently of the book.

Discuss in groups of three: There is a hungry tiger in your office.  If one person gets eaten by the tiger, the other two people can run to safety.  Which person should volunteer to let the tiger eat them?	Discuss in groups of three: Zombies are attacking your office building.  You have two options--run and hide in the basement, or try to find safety on the roof.  What should you do?
Discuss in groups of three: There’s a shape-shifting alien in your company.  It can take change its shape so that it looks like a human being.  You suspect that one of your co-workers has been replaced by this alien, but you don’t know which one.  Discuss with your group members until you can agree on who it is.	Discuss in groups of three: Office pizza party time!  Everyone is hungry, but there’s only one piece of pizza left.  Who should get it?  Discuss with your group members.
Discuss in groups of three: The teacher ate too much pizza last night, and is home sick all day today.  One of you will have to teach the class instead.  Who should it be?  Discuss with your group.	Discuss in groups of three: You’re planning the end of year office Christmas Party.  Where should the party be?  What kind of food and drinks should you have?
Discuss in groups of three: Great news.  You got a new TV in the office, for the employees to watch while they work. But since there’s only one TV, everybody will have to watch the same thing. What program should you put on?	Discuss in groups of three: Your office is being attacked by a giant spider.  What should you do?
Discuss in groups of three: Good news.  You have $100,000 extra in the company budget this year.  How should you spend it?	Discuss in groups of three: Bad news.  The company unexpectedly lost $100,000 this year.  You need to make that money back somehow.  What should you do?