In this Grade 4 lesson from Pengi Math Chapter 2, students learn to deconstruct and solve multi-step word problems involving two or more operations. They practice representing problems as equations with a variable for the unknown quantity, then evaluate whether their answers are reasonable using estimation and mental computation.
Section 1
Modeling Two-Step Word Problems with Tape Diagrams
In a two-step word problem involving parts and a whole, a tape diagram represents the total amount (the whole) and its components (the parts). To find an unknown part, you often first find the sum of the known parts, then subtract that sum from the whole. This relationship can be shown as:
Section 2
Solving Two-Step Comparison Problems
To solve a multi-step comparison problem, first combine parts into a total using addition, then find the difference using subtraction. This can be represented as finding the difference where one quantity is a sum: .
Section 3
Check: Using Estimation to Assess Reasonableness
To assess the reasonableness of a precise answer, compare it to an estimate made by rounding the numbers in the problem.
If the precise answer is close to the estimated answer, it is likely reasonable.
This can be represented as:
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Section 1
Modeling Two-Step Word Problems with Tape Diagrams
In a two-step word problem involving parts and a whole, a tape diagram represents the total amount (the whole) and its components (the parts). To find an unknown part, you often first find the sum of the known parts, then subtract that sum from the whole. This relationship can be shown as:
Section 2
Solving Two-Step Comparison Problems
To solve a multi-step comparison problem, first combine parts into a total using addition, then find the difference using subtraction. This can be represented as finding the difference where one quantity is a sum: .
Section 3
Check: Using Estimation to Assess Reasonableness
To assess the reasonableness of a precise answer, compare it to an estimate made by rounding the numbers in the problem.
If the precise answer is close to the estimated answer, it is likely reasonable.
This can be represented as:
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter