Add and Subtract Decimals

6.NOS.3 · Unit 2 · Lesson 11

Name   Period

Objectives / Objetivos

Content Objective: I can add and subtract decimals by lining up the place values and the decimal points.

Language Objective: I can explain my steps using the words decimal, place value, tenths, hundredths, and add zeros.

Key Idea / Idea clave

Adding & Subtracting Decimals. 1. Line up the decimal points vertically by place value. 2. Insert placeholder zeros so each number has the same number of decimal digits. 3. Add or subtract right-to-left, regrouping as needed, and drop decimal straight down

I Notice / Observo

  • What is the starting fuel amount?
  • Which operation adds fuel and which removes fuel?

I Wonder / Me pregunto

  • Why is it important to line up the decimal points?

Vocabulary / Vocabulario

Term / TérminoDefinition / Definición
Add and Subtract Decimals
Sumar y restar decimales		Combine or find the difference between decimals by lining up equal place values.
Combinar o hallar la diferencia entre decimales alineando valores posicionales iguales.
Decimal
Decimal		A number with a dot, like 0.5, that shows a part less than one.
Un número con un punto, como 0.5, que muestra una parte menor que uno.
Place value
Valor posicional		What a digit is worth based on where it sits in a number.
Lo que vale un dígito según el lugar que ocupa en el número.
Tenths
Décimas		The first spot after the decimal point. It shows parts out of 10.
El primer lugar después del punto decimal. Muestra partes de 10.
Hundredths
Centésimas		The second spot after the decimal point. It shows parts out of 100.
El segundo lugar después del punto decimal. Muestra partes de 100.
Annex zeros
Agregar ceros		Adding zeros at the end of a decimal so numbers line up evenly.
Agregar ceros al final de un decimal para que los números se alineen.

Practice Preview / Vista previa de práctica

  1. What is 14.6 + 3.85?
    1. 18.45
    2. 18.35
    3. 17.45
    4. 18.55
  2. Compute each decimal sum or difference.
  3. Estimate each sum or difference by rounding to the nearest whole number, then sort: is the result greater than 10 or less than 10?
  4. Find Tasha's Mistake
    1. Step 1: Problem — 15.7 − 8.36
    2. Step 2: Set up — 15.7 − 8.36
    3. Step 3: Subtract — 15.7 − 8.36 = 7.41
    4. Step 4: Final answer — 7.41

    Which step has the mistake? Explain it and write the correct work.

Reflection / Reflexión

One thing I learned today / Una cosa que aprendí hoy: