Modeling equations with a pan balance: video lessons
In the first video, I explain the basics of how we model simple equations with a pan balance (scales). Each side of the balance represents one side of the equation. The two sides are EQUAL (weigh the same).
In the second part, I show how to solve equations when there are several unknowns (x's) in one pan in the balance or scales (on one side of the equation). What to do? It is simple!
In the last part (video below), we look at equations where we need to remove some unknowns (x's) or some amount ("weight") from both sides — or do both. Using the scales (pan balance) as a visual model will help you see this principle! When the same amount is removed from BOTH sides, the balance will stay balanced — which means we can still write the equals sign between the expressions.
See also
Problem solving with bar models: fractional part of a whole
More problem solving with bar models, part 1
More problem solving with bar models, part 2
Math Mammoth Grade 5 curriculum