Students will interpret numerical expressions without solving them and write simple expressions.
Introduction (5 minutes)
- Review the commutative property of multiplication and the order of operations.
- Teach students that expressions are a series of numbers and symbols, such as +, -, x, and ÷, without an equal sign.
- Write the expression 5 (4 + 3) on the board.
- Tell students that when that expression is worked out it is called an evaluation of the expression.
- The expression equals 35, therefore 5 (4 + 3)= 35 is the equation.
- Tell students that the expression 5 (4 + 3) is 5 times larger than the expression (4 + 3).
- Let students know that today they are going to evaluate the relationship between expressions and write their own expressions to evaluate.
Explicit Instruction/Teacher Modeling (10 minutes)
- Write the steps “double five and then add 50” on the board.
- Ask students to write an expression for the steps above.
- They should write (5 x 2) + 50 or 5+5+50.
- Write the expression "6 (10x10)" on the board.
- Ask students to describe, in writing, how the expression relates to (10x10).
- They should write that the expression 6 (10x10) is 6 times larger than the expression (10x10).
- Choose volunteers to create their own expressions like the two you just modeled and explain them.
- Guide students through the process of evaluating their expressions orally.
Guided Practice/Interactive Modeling (10 minutes)
- Allow students to form pairs or small groups.
- Pass out the Welcome to Mummy’s Market worksheet.
- Advise students that they should work with a partner or group to write an expression and evaluate the expressions.
- Remind students to refer back to their notes from the models you provided.
Independent Working Time (20 minutes)
- Pass out blank paper.
- Tell students that they are going to work alone to create their own expressions and evaluate the relationships between the numbers just like they have been practicing.
- Students may need an example to get them started. Example: Write an expression in words, such as "divide 144 by 12, and then subtract 20." Students should write (144 ÷ 12) – 20 and go on to write that the expression (144 ÷ 12) – 20 is 20 less than (144 ÷ 12).
- Enrichment: Advanced students can evaluate expressions that contain fractions, decimals, etc.
- Support: Struggling students can use the Multiply It! worksheet during the guided practice.
Related Books and/or Media
Assessment (15 minutes)
- Pass out the Express Yourself assessment.
- Advise students to use a blank sheet of paper to show their work.
- Remind them that they must follow the directions and answer the questions completely.
Review and Closing (5 minutes)
- Write the following expression on the board: (200 ÷ 10) x 0.5.
- Have students identify the expressions and equation.
- Then have students evaluate the expression without calculating it: (200 ÷ 10) x 0.5 is ½ of (200 ÷ 10).
- Ensure that students can create a word problem or steps for this equation: divide 200 by 10 then multiply by a half.