Bridge: Numerical Expressions with Grouping

How the lesson starts: Bridge: Numerical Expressions with Grouping

Snack pods for space!
Hi, space cadet! Captain Zara is packing snack pods for 3 rockets. Each pod gets 8 star cookies and 2 moon cookies. How many cookies does she need in all? A pair of curvy parentheses will help us write it!
Parentheses go first
Write it as math: 3 × (8 + 2). The parentheses are like a snack pod. They hold a group together. Always open the pod first! 8 + 2 = 10. Then multiply: 3 × 10 = 30. Skip them, and you'd get 3 × 8 + 2 = 26. Wrong!
Words into math
Zara's recipe card says: add 8 and 7, then multiply by 2. The word then tells us the order. Add 8 and 7 first, so they go inside parentheses: (8 + 7). Then multiply by 2: (8 + 7) × 2. That's 15 × 2 = 30.