Download Common Errors When Writing and Solving Equations

Common Errors When Writing and Solving Equations
1. Students add to one side and subtract from the other side when
solving addition and subtraction equations. Remind them that
equations are like a balanced scale. If you add weight to one side
of the scale (adding a constant) you must add weight to the other
side. If you take weight away (subtracting a constant) you must do
so from both sides. Remind them that the ultimate goal is to isolate
the variable on one side of the equation (you may need to define
isolate for them.)
2. Students try to subtract a coefficient rather than divide by it. For
example, if an equation reads 3x =51, students may make the
following error: 3x = 51
-3
-3
x = 48
Remind students that “3x” means 3 times x. Also remind them that
to undo what is being done in an equation, they should use the
inverse function (you may have to define inverse function.)
3. Probably the most common error students make is in division
equations. For example:
𝑥
5
= 20
Often students will look at it and say 5, 20, the answer
is 4. They are used to making fact families, so they often times just
make that “fact family” leap. Remind them that this is a division
equation and that to solve a division equation, you must UNDO the
division. Then ask them how to undo division and they will almost
always say “multiplication.” Ask them, then, why they didn’t
multiply both sides by 5 and they will all have that “aha” moment.
You will likely need to do this MULTIPLE times.
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