Lesson Objective: Students will be using the calculator to enter expressions and find that the calculator uses the order of operations to perform a string of operations.

Supplies and Materials:

Students will be given four activities to work on with a partner.

Activity 1: Students will be given 8 expressions involving multiplication and division to enter in their calculator and record the answers given by the calculator. Students will be asked to study the expressions and answers and decide what order the calculator is doing to get the answer given. Students should observe that the multiplication and division are being done in the order they are given from left to right. If multiplication is written first it is done first. If division is written first it is done first. Students will be asked to make up their own number sentence using multiplication and division and record the correct answer based on their conjecture.

Activity 2: Students will be given additional expressions with multiplication and division but this time parentheses will be added to the expressions to study what effect these have on the calculation. After entering the expressions, recording the answers, students are asked to conjecture about what the calculator is doing to get the answer. Students will be given the numbers 36, 5, 12, and 4 and asked to use multiplication and division along with parentheses to get both 18 and 72 using their conjecture.

Activity 3: Students will be given expressions involving only addition and subtraction to enter in their calculator and record the answers. In the second group of expressions the students will enter the same expressions but with parentheses. Students will be asked to study the expressions and make a conjecture about what the calculator is doing to obtain its answers with and without the parentheses. Finally they will try to write a number sentence that equals 4 using 1, 2, 3, and 6 and addition, subtraction, and parentheses.

Activity 4: Students will be given two sets of expressions to enter in their calculator. Students will record the answers and then make an observation about what the calculator is doing to obtain the answers. Once they have conjectured about this, the students will try to write expressions that use 2, 3, 5, and 10 and the operations of +, -, x, and ÷ to yield the answers of 1 and 40. Finally students will be asked to use the numbers 9 + 18 ÷ 3 - 3 along with parentheses to yield the answer 0 and 4.5.