Provide a number of challenging words and for students to create a coherent argument using them all.
Dice game - students have a die and they roll it. They will have to create an argument using all the words listed after the number they have rolled.
Create a story using the words provided or using ten words you didn't know (dictionary or technology needed)
When working, replace a words in every sentence by more challenging words
Taboo - you give a student a term and they need to get the class to guess it
Memory challenge - put the students into pairs or small groups. Give them a time limit (e.g. 3 minutes) and ask them to write down as many words, phrases, and/or expressions as they can from the last lesson on topic X. The pair or group that can remember the most items wins.
Two words game - write up two separate word lists on the board; an A list and a B list. Assign half the class the A list and the other half list B. Each student takes each word from their list and contextualises it into a coherent question.
Good old Bingo!