Mr. Elmer

Students will decompose what has happened to a variable in order to solve the equation.

Start with the geologic cross-section.

Explain that geologists work backwards with a geologic cross-section to uncover what order events happened in a geologic area. In the sample cross-section, the newest events were B and C. A had to happen after Layer D was deposited or it couldn't have cut through it like it did. Discuss what order things could have happened.

In the same way, we will "decompose" equations to see what needs to be done 1st.

Show the problem 4x+6=-10. This is from Worksheet A

Ask, "Where's the variable and what is happening to it?" The most immediate thing happening to x is that it is being multiplied by 4. Then, 6 is being added to that product. So, to find x we need to unravel the equation. You can make a table like the one found here:

Unravel Equations--belmersandbox

Have students go to

2-Step Equation Practice B or have it printed for them. Look at number 3. The first thing done to the variable is 5 added to *a.* Then, that sum is being divided by 3. So, to undo those operations, we need to first multiply by 3, then subtract 5.

Now, look at number 1. The number of uniforms is multiplied by $24.25. Then $598 was added to the cost of the uniforms to get the total cost of $1762. This is a good way to create the expression and the equation that must be set up in order to solve. So, undo by subtracting the $598. Then divide by the $24.25.

Here is a short 5-question quiz to test your equation-unraveling prowess!

It's important that students know and understand "sum," "difference," "product," and "quotient," in order to construct and deconstruct the expressions and equations.