Split the class into teams and ask a student to choose easy, medium or hard. Give them around 30 seconds to describe the object (only words, no actions) in front of their group without naming it (while other teams stay quiet). If they say the object's name or their team can't guess correctly they get 0 points but if their team guesses correctly then they get however many points their object was worth.
Continue the process with the other teams while keeping track of the scores and see which team wins!
You might like to let other teams guess the object if the original team are unsuccessful in their 30 seconds, giving them the chance to earn more points.
If the students are finding it easy you can write some words next to the object that the student isn't allowed to use when describing it. Here are a few example objects you might like to use:
Ball - Can't use round, bounce or sport
Food - Can't use eat, delicious or snack
Computer - Can't use keyboard, screen or Internet
Money - Can't use cash, coins or credit
House - Can't use home, roof or room
Pen - Can't use write, ink or pencil
Sun - Can't use big, hot or sky
Moon - Can't use night, bright or light
Mountain - Can't use climb, big or hill
Window - Can't use glass, wall or look
Car - Can't use drive, wheel or license
Tree - Can't use leaves, nature or roots
Shoes - Can't use feet, socks or toes
Camera - Photo, picture, take