If you place a fraction problem like this in front of your students, some will make the correct decision, some won't. Some were paying attention when you gave your lecture, some weren't.
Now, if you place the following option in front of each student (a large piece of cake or a small one) you better bet their going to listen to everything you say!
1) My suggestion, buy or bake a cake or cookie, pizza, etc. (ask the manager for discounts since it will be learning related in exchange for sending pizza magnets or coupons home to each parent).
2) Cut Two pieces for each student, a large piece and a small piece
3) Give each student a fraction problem like the one above and explain that by giving you the answer the are choosing which piece they get and you can not go back once your decision had been made.
4) Thus, the students being rewarded with a bigger piece of cake because they got the problem right...THEY are choosing the bigger or small piece of cake when they give you a <, > or = sign!
Your students now have a huge incentive to listen to what you are saying!