Balance addition equations - up to three digits

Learning Objectives Define 'equation', 'variable', and 'balance' in the context of mathematics. Explain that the equals sign (=) means 'is the same value as'. Solve for an unknown variable in an addition equation with numbers up to three digits. Use subtraction as the inverse operation to find a missing addend in an equation. Verify a solution by substituting the value back into the original equation to check for balance. Create a balanced addition equation that includes a variable. Imagine a seesaw with two friends. How do you make it perfectly level? ⚖️ We're going to learn how to do the exact same thing with numbers! In this lesson, you will learn how to make addition equations 'balance' on both sides of the equals s...

TermDefinitionExample EquationA number sentence that uses an equals sign (=) to show that two amounts or expressions are equal.150 + 100 = 250 is an equation because both sides have the same value. VariableA symbol, usually a letter, that stands for an unknown number in an equation.In the equation 215 + x = 300, the letter 'x' is the variable. Equals Sign (=)The symbol that means 'is the same as' or 'has the same value as'. It is the center point of a balanced equation.The expression 75 + 25 has the same value as 100, so we write 75 + 25 = 100. BalanceWhen the value on the left side of the equals sign is exactly the same as the value on the right side.The equation 400 + 50 = 300 + 150 is balanced because both sides equal 450. Inverse OperationAn operation tha...

The Balancing Rule Left Side = Right Side This is the most important rule for equations. To keep an equation balanced, whatever operation you perform on one side of the equals sign, you must perform the exact same operation on the other side. Inverse Operation Formula for Addition If a + x = c, then x = c - a To find a missing part (addend) in an addition problem, you subtract the part you know from the whole (the sum). This helps you get the variable by itself.