Mathematics
Grade 4
15 min
Balance addition equations - one digit
Balance addition equations - one digit
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Define an equation and explain that the equals sign means 'the same as'.
Identify a variable (e.g., x, ☐) as a placeholder for an unknown number.
Solve for a missing addend in a one-digit addition equation.
Solve for a missing sum in a one-digit addition equation.
Use the inverse operation (subtraction) to find a missing addend.
Verify a solution by substituting the value back into the original equation to check for balance.
Imagine a seesaw with two friends on it. What has to be true for it to be perfectly level? 🤔 Equations are just like a perfectly balanced seesaw!
In this lesson, you will learn how to keep addition equations perfectly balanced. We will use symbols called variables to represent missing numbers, and you will become an expert...
2
Key Concepts & Vocabulary
TermDefinitionExample
EquationA mathematical sentence stating that two expressions are equal. It always contains an equals sign (=).The sentence 3 + 4 = 7 is an equation.
Equals Sign (=)A symbol that means 'is the same as' or 'has the same value as'. It shows that the left side of the equation is balanced with the right side.In 5 + 1 = 6, the value of '5 + 1' is the same as the value of '6'.
VariableA symbol, like a letter (x, n) or a shape (☐, ?), that stands for a number we don't know yet.In the equation 8 + x = 9, the letter 'x' is the variable.
AddendA number that is added to another number in an addition problem.In the equation 2 + 5 = 7, the numbers '2' and '5' are both addends.
SumThe total or the answer you...
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Core Formulas
The Equality Rule
a + b = c
This rule shows that the value of the expression on the left side (a + b) must be exactly the same as the value on the right side (c). The equals sign is the center of the balance.
Finding a Missing Addend
If a + x = c, then x = c - a
To find a missing part (an addend, 'x'), you can use the inverse operation. Subtract the addend you know ('a') from the total sum ('c').
Finding a Missing Sum
If a + b = x, then x is the result of adding a and b.
To find the missing total (the sum, 'x'), you simply perform the addition shown on the other side of the equation.
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Challenging
Look at the balanced equation: 2 + 7 = x + y. If x and y must be different whole numbers, which of these could be the values for x and y?
A.x = 2, y = 7
B.x = 9, y = 0
C.x = 4, y = 4
D.x = 3, y = 5
Challenging
Sam and Tom have 8 toy cars altogether. Sam has 2 more cars than Tom. If 't' represents the number of cars Tom has, which balanced equation correctly shows the total number of cars?
A.t + (t + 2) = 8
B.t + 2 = 8
C.8 + 2 = t
D.t + t = 8
Challenging
To keep the scale balanced, what number must 'n' be in the equation: 1 + 8 = 4 + n?
A.9
B.12
C.5
D.4
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