Play a sample game with the students so they learn the game. Invite them to pudding shuffle the cards with you.
After the cards are straightened back into one deck, they are divided approximately in half in one clean split, not divided one card at a time into two piles. This emphasizes that the game isn't about trying to win the most cards. It also saves valuable teaching time.
The two piles are placed face down across from each other. Divide your students into two small groups. Ask two students from each group to take the top card from their pile and place it face up between the piles. Players can use the guide card that comes with the deck or rely on their memories.
Whoever has the larger card wins both cards. Teach them how to pull the two winning cards close to themselves, leaving them face up on the floor so both cards are showing.
This is important for later when you are watching many pairs of students play War at the same time. This gives you a moment to see if the play was done correctly rather than if those two cards are turned face down.