These games have all worked well for me with that age group:

Get a bomb flashcard and everytime you show the bomb the kids have to cover their heads and jump to the ground.

Slow and fast reveal: First, reveal the flashcards really slowly. Afterwords quickly flash and hide the flashcards so they see it for less than a second, they like both ways.

Where's the ball - Get a paper cup for each word you're drilling and a ping pong ball. Put the cups upsidedown in front of each item on the floor, and hide ball under one of the cups. Ask them where the ball is then, lift the cup to check, then go again but mix the cups around.

What's missing - Lay the flashcards out, ask them to close their eyes and take one away.