GOAL OF THE GAME:
Be the first player to collect 5 challenge cards by guessing body /object measurements the most accurately using the number cards.

HOW TO PLAY:
The player with the biggest smile starts. The player must draw a challenge card from the pile and place it face up in the middle of the table. The player who draws the card decides which person or object will be the subject of the challenge. The player can’t decide to measure themselves. The player announces if this round is played in centimeters or millimeters. If the drawn challenge card cannot be played (for example, none of the players has a tattoo), treat this card as a freestyle card.

Next all players — including the one who drew the card or chose the part to measure — secretly estimate the measurement. The players choose one of their number cards and play it face down on the table. The players can also answer by playing 2 number cards and their values are added together.
Example: 17 + 30 = 47

Once all players have played a number card face down, the cards can be revealed.
The initial player measures the body part or object. The player who guessed the number closest to the real size or length wins the challenge card.

Example: the correct answer is 35. If one player answered 38 and one player answered 30, the player with the 38 wins this turn.

ENDING TURNS:
The used number cards are discarded in a pile and all players refill their hands so they have 10 cards. The players draw 1 number card if they played 1 number card, or they draw 2 number cards if they played 2 number cards. If the draw pile is empty, shuffle the discard pile and create a new draw pile.

The game continues clockwise (the player to the left of the first player draws the next challenge card, and so on).

VICTORY:
The first player to collect 5 challenge cards wins.

—user summary

The concept of Size Up is simple: Estimate the length of your grandmother's little finger, the width of your train ticket, or the circumference of a carrot. The tape measure is used to check the estimates afterwards. Whoever has the best sense of proportion wins!

—description from the publisher

Wonder Woods