Stage 3 · Structure / #19
Solving an Equation Is Balancing a Scale
Planned
The video is in production. Follow along on GitHub to hear when it is out.
The idea
The equals sign says both sides weigh the same, like a level balance. Take the same amount off both sides and it stays level, so you may subtract the same number from both sides until the box is left alone.
A common mix-up
The equals sign means 'write the answer here', so in 3 + 4 = blank + 5 the blank is 7.
Where it stops working
Take weights off only one side and the balance tips straight away: the sides no longer weigh the same, and the equation is no longer true.
School year
China 7