Yeah phrasal verbs are a hard nut to crack.Try the following:
1. Put them into groups with the following names "up" "out" "on" "in" "down"
these are the famous five that mostly accompany phrasal verbs. Give them the following homework. (Ideal for a weekend). Put a Bronze prize. Candies or something. The group that finds out the highest number of family members wins. (Family members here refer to verbs that take their group name).
Let them search for these verbs even without knowing their meanings. But I bet they always find out the meanings even before you ask them. Once they get this done your first objective is reached. They have seen how important the prepositions are to the main verbs and their interchangeability. Move to step two.
2. The family that finds "Nicknames" for all its members wins the silver prize. Get chocolate or something. Nicknames here refer to other verbs that mean the same as the phrasal verb that is their family member. Count two nicknames for the same verb as two points. That's their vocabulary growing. Move to step 3.
3. (if you have high level students) Ask each group to write a paragraph in which we can find all their family verbs or their nicknames. Best paragraph wins the final prize (Gold) Pizza or something.
(if you have lower or average level students). Let them write short sentences with each one of their family names. The group with all correct sentences wins the gold.
In my case it took me three weeks to get over this project because I was using only Fridays and making them work over the weekends. Till this day some of those "names" verbs are still used in my class. James Look Down On is my nauthiest
Warning: Expect embarrassment with verbs that you can't make out the meanings immediately. So get yourself a good dictionary first before you start the project.
Good luck and have fun!