Write simple expressions that record calculations with numbers, and interpret numerical expressions without evaluating them. For example, express the calculation "add 8 and 7, then multiply by 2" as 2 × (8 + 7). Recognize that 3 × (18932 + 921) is three times as large as 18932 + 921, without having to calculate the indicated sum or product.
Students will learn how parentheses affect the value of an expression. For example, \((2 + 3) \cdot 4 \ne 2 + 3 \cdot 4.\) Here's a lesson, and here's practice. Then students will learn how to convert from American English phrases to expressions involving parentheses. Here's a lesson. Students can practice by doing this and this. Conclude by giving your students this challenge.