Problem 1
Is 8 = 6 + 2 true or false? Explain.
Show worked solution
True. Both sides name eight, even though the total is written first.
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math-2017:1.OA.7 Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. For example, which of the following equations are true and which are false? 6 = 6; 7 = 8 - 1; 5 + 2 = 2 + 5; 4 + 1 = 5 + 2.
math-2017:1.OA.8 Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations: 8 + □ = 11; 5 = □ − 3; 6 + 6 = □.
Learning goal: Interpret equality as the same amount on both sides, decide whether addition/subtraction equations are true, and find an unknown whole number in different positions. Work with counters and written equations. The position of a box does not change the meaning of the equal sign.
Place five counters on each of two mats. Write 5 = 5 and explain that both sides name the same amount. On one mat, organize the counters into a group of two and a group of three. The amount remains five, so 5 = 2 + 3 is true. The left side does not have to contain an operation and the right side does not have to contain a single answer numeral.
Read 7 = 8 − 1 by evaluating both sides: seven on the left and seven on the right. It is true. Read 5 + 2 = 2 + 5 the same way: seven on the left and seven on the right, so it is true even though both sides contain an operation. Read 4 + 1 = 5 + 2 as five on the left and seven on the right. It is false. An equation is not true just because the arithmetic expressions are familiar or the writing looks balanced on the page.
The illustration shows three equation cards, each paired with an explanation. The cards are separate examples, not a chain of equalities. Count or compute the quantity on each side of each card before deciding. A matching color or equal-sized box is only a design choice; it cannot establish equal numerical value.
For 8 + □ = 11, ask what whole-number amount added to eight makes eleven. Three fills the box. Check by substituting: 8 + 3 = 11. For 5 = □ − 3, the unknown is the starting quantity before removing three. Eight fills the box because 8 − 3 = 5. Choosing two from 5 − 3 would answer a different equation.
Unknowns can also appear as results, such as 6 + 6 = □, or in either addition part. Explain the role of the unknown before computing. A box is a placeholder for a number in this equation, not a decoration or a command to add an extra object. Once filled, the full equation must express the same amount on both sides.
Worked example 1: True in a less familiar order. For 9 = 4 + 5, compute the right side as nine and compare it with the left nine. The equation is true even though the total is written first.
Worked example 2: A false statement. For 3 + 4 = 4 + 4, the left side is seven and the right side is eight. They are unequal, so the statement is false. To make a new true equation, one could change the final four to three, but that is a revision of the original statement.
Worked example 3: Unknown starting amount. For □ − 4 = 6, rejoin the four removed counters and the six remaining counters. The start was ten. Substitute ten and verify 10 − 4 = 6.
Guided practice: Build two equal amounts in different arrangements and record multiple true equations. Include equations with operations on either side and on both sides. Then place a box in a starting, changing or result position and ask learners to explain what it represents.
Independent tasks: Classify several equations as true or false and justify the choice by comparing amounts. Solve unknown-number equations and substitute each answer to check. Use drawings or counters for at least one unfamiliar form. The practice set includes both operation-first and total-first arrangements.
Assessment and feedback: Credit a correct truth judgment or unknown value together with a valid equality explanation. If the child reads equals as “write the answer next,” use two mats naming matching amounts and reverse a familiar true equation. If the box is solved using nearby numbers without regard to the relationship, rebuild the equation with objects. Extend by asking the learner to create one true and one false equation and explain the distinction.
An adult may read the prompts aloud. Answer independently with words, objects, drawings or a demonstration before opening the answer guide. Award 1 point for a correct result or claim and 1 point for a matching explanation or demonstration; where a question asks only for a result (a corrected sentence, a spelling, a count), a fully correct result earns both points, and the answer guide shows what a complete response contains. Record prompting separately. The total (two points per question) is local practice feedback, not an Ohio proficiency level.
Is 8 = 6 + 2 true or false? Explain.
True. Both sides name eight, even though the total is written first.
Is 6 + 1 = 4 + 2 true or false? Explain.
False. The left side is seven and the right side is six.
Is 9 − 3 = 2 + 4 true or false? Explain.
True. The left side is six and the right side is six, so both sides name the same amount.
Find the unknown in 7 + □ = 12.
Five; substituting gives 7 + 5 = 12.
Find the unknown in 4 = □ − 3.
Seven; 7 − 3 = 4. The unknown is the amount before removing three. Answering one, from 4 − 3, would solve a different equation.
Find the unknown in □ − 5 = 4.
Nine; 9 − 5 = 4. Rejoin the five removed and the four left to check.
What does the equal sign mean?
The expressions on the two sides represent the same amount, not simply that an answer is written next.