Combine or find the difference between decimals by lining up equal place values.
Example: 12.40 + 3.75 with the points lined up
Add and Subtract Decimals
I can add and subtract decimals by lining up the place values and the decimal points.
Speaking and writing goal: I can explain my steps using the words decimal, place value, tenths, hundredths, and add zeros.
What Your Child Is Learning
In this lesson, students practice how to add and subtract decimals by lining up the place values and the decimal points. They learn to show their thinking with numbers, pictures, words, or a model. The goal is not just getting an answer. Students should be able to explain why the answer makes sense.
Why This Matters
This skill supports everyday problem solving with money, measurements, games, planning, and checking whether an answer is reasonable.
What It May Look Like In Class
Your child may use the interactive lesson, guided notes, examples from the board, partner talk, and short practice problems. They may be asked to solve, draw a model, label important numbers, and explain their reasoning in a sentence.
How You Can Help At Home
You do not need to teach a new method. Ask your child to read the problem out loud, circle the important numbers, and explain what they tried first. Helpful questions include: What do you know? What are you trying to find? Does your answer make sense?
Apoyo para familias en español
Qué está aprendiendo su hijo/a
En esta lección, su hijo/a practica usar números con cuidado y explicar sus pasos. Puede usar dibujos, números, palabras o modelos para mostrar su pensamiento. Lo más importante es que pueda explicar por qué su respuesta tiene sentido.
Por qué es importante
Esta habilidad ayuda con dinero, medidas, juegos, planificación y con revisar si una respuesta es razonable.
Cómo puede ayudar en casa
No necesita ser experto/a en matemáticas. Pídale a su hijo/a que lea el problema en voz alta, marque los números importantes y explique su primer paso. Puede preguntar: ¿Qué sabes? ¿Qué necesitas encontrar? ¿Tu respuesta tiene sentido?
Key Vocabulary
A number with a dot, like 0.5, that shows a part less than one.
Example: 0.5 for one half
What a digit is worth based on where it sits in a number.
Example: The 5 in 12.5 meaning five tenths
The first spot after the decimal point. It shows parts out of 10.
Example: The 3 in 0.3
The second spot after the decimal point. It shows parts out of 100.
Example: The 7 in 0.07
Adding zeros at the end of a decimal so numbers line up evenly.
Example: Writing 12.4 as 12.40 to subtract 8.36
Try It Together
Pick one or two problems. Let your child explain the first step before opening the answer.
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Estimate first, then solve: 48 / 6.
Show answer
Estimate about 50 / 5 = 10; exact answer 8
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Explain one way to check an answer.
Show answer
Use the opposite operation, a model, or estimation.
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Write a number story for 12 x 3.
Show answer
Answers vary; for example, 12 rows of 3 chairs.
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What should you do if an answer seems too big or too small?
Show answer
Re-read the problem and check with an estimate.