Just Undo It Page 144

Choose a secret number. Now choose four more non-zero numbers and in any random order add one of them, multiply by another, subtract another, and divide by the final number Record in words what you did and your final result on the communicator with a blank Evaluate an Expression template. (Do not record your secret number.) Switch communicators and have another students find your secret number.

? Add 7Ans+7 x x+7 Divide by 4 Ans÷4 Add 5 Ans+5 Mult by 4Ans x 4 Subtract the original # Ans – org # Add 13Ans+13

Solve Equations is Just Undoing Operations Use the Undo Chart complete the following number trick. Complete the first three columns only. Pick a number Divide the number by 4 Add 7 Multiply the result by 2 Subtract 8 DescriptionSequenceExpression Pick a numberXX

Solve Equations is Just Undoing Operations DescriptionSequenceExpression Pick a number ?X Divide the number by 4 /4 Add 7+7 Multiply by 2x2 Subtract 8-8

Solve Equations is Just Undoing Operations Can you start at the bottom of the chart and undo each operation? Write the description in the Undo column. Pick a number Divide the number by 4 Add 7 Multiply the result by 2 Subtract 8 DescriptionSequenceExpressionUndo Pick a numberXX

Solve Equations is Just Undoing Operations DescriptionSequenceExpressionUndo Pick a number XX Divide the number by 4 /4x4 Add Multiply by 2x2/2 Subtract 8-8+8

Solve Equations is Just Undoing Operations Suppose the answer to the problem was 28. What number did we begin with? Place 28 in the bottom box in the last column. Complete the Result Column. Pick a number Divide the number by 4 Add 7 Multiply the result by 2 Subtract 8 DescriptionSequenceExpressionUndoResult Pick a number XX

Solve Equations is Just Undoing Operations DescriptionSequenceExpressionUndo Pick a number XX Divide the number by 4 /4x4 Add Multiply by 2x2/2 Subtract

Try another One! Set up the problem: DescriptionSequenceExpressionUndoResult Pick a number XX

Turn to page 144 and in your groups begin with step 1. Use the Just Undo It Chart in the Communicators® to record your description, sequence, and expression. Complete step 2. For Step 3, exchange your Communicators® with a partner or another group and complete the undo for each step. For step 4, start with a number in the bottom right corner (the answer to the number trick) and work the table backwards to find out what number the person would have to start with to get that result.

Undoing an Equation Place the Undoing an Equation Template in your Communicator®. Record an equation in the cell at the top. Complete the description column using the order of operations. Complete the undo column. Finally, work up from the bottom of the table to solve the equation. Write a few sentences explaining why this method works to solve an equationUndoing an Equation Template

-3 x ÷ x

An equation is a statement that says the value of one expression is equal to the value of another expression. Solving equations is the process you used to determine the value of the unknown that makes the equation true. This is called the solution.