S1 · Algebra · ALG.EQ.ONE_STEP

Solve one-step equations

Intuition

Understand first, compress later.

Algebra describes structures generally: a symbol stands for a number, while the rules remain the same.

Switch representations

Equation as a balance3x = 20

x tile — the unknown numberunit token — worth 1ten-block — ten unitscoral with a bar — negativebeam — the equals sign

The beam hangs level because both pans weigh the same — that is exactly what the equals sign claims. Take something off the left and you must take the same off the right, or it tips. Ten units are bundled into one ten-block; if a quantity still will not fit in the pan, a single labelled token carries the number instead. Below, the same step is hung on both pans of a small beam, with the equation it produces set beside it.

Formal view

You can solve one-step equations when you can recognise the underlying objects, select valid rules and check each step for equivalence or logical implication.

Why does it work?

This skill sits on a prerequisite network. If a step is unstable, repair the missing prerequisite instead of merely doing more items of the same type.