One of the downfalls of the typical passing drill is that the players are always standing still. One player stands at one spot and the other player at another spot and they pass back and forth. The drill is static, which is not what happens in an actual game of soccer. In an actual game, players are in movement. If you coach passing with players standing still, they will either A) stand still in the game passing and/or B) will not move to receive the next pass. Players need to be in movement at all times.
"Gates" is the perfect game to teach passing and movement. Set up more gates than you have pairs. Don't have a ratio less than 3:2 - 3 gates for every 2 pairs. At the start, Player One starts with the ball, Player Two finds an open gate (if another pair is at the gate already, find another gate). Player One dribbles close to the gate and passes the ball through the gate to Player Two, Player One goes to find an open gate and so on and so on. Focus on proper passing technique, players getting their heads up looking for the next gate, and quick dribbling movements.
Pairs should see how many gates they can do in one minute. A good rule of thumb is the age of the player to gates. So a pair of 8 year-olds should be able to do 8 gates in one minute. I've seen some older players get up to 20 gates in one minute, but this was with highly accurate passing. Have players do this drill and see if they can always improve by one gate each one minute session.