Road Trip I Spy Number Game

We make many long road trips. When Jamie and Tanner were about 8, 9, or 10, we made up a road trip game. The rules of the game are as follows:

1. Pick someone to go first. 
2. The first player looks outside the car and identifies an object and says, “I see one ______.” (For example, the player could say, “I see one cow.” There must be one cow in view for all players to see. 
3. The next player has to now find two of the item found by player one and then find one of a different item. To continue the example, the second player finds two cows (if you are not currently driving past cows the player has to wait until you drive past at least two cows). Then, the player can find one road sign. 
4. The next player has to find three of the first item, two of the second item, and one new item. For example three cows, two road signs, and one red car. 
5. The next player finds four of item one, three of item two, two of item three, and one new item. For example, four cows, three road signs, two red cars, and one fence post. 
6. Play continues until a player finds 10 of item one. 
7. For each item, the player can only count it if one of the items is visible outside the car. 

For many years, this game became one of our favorite road trip games. 

Allyn and I used to play this in every trip from College Station to Temple to see her eye doctor (once a quarter from age 11 until she graduated from high school.