Two numbers that describe spread: the range covers all the data, and the interquartile range covers only the middle half.
Example: Range 26 with IQR 12.5
Describe Data by Range and Interquartile Range
I can find the range and the interquartile range of a data set and use them to describe how spread out the data is.
Speaking and writing goal: I can explain what the spread of a data set is using the words range, quartile, interquartile range, and vary.
What Your Child Is Learning
In this lesson, students practice how to find the range and the interquartile range of a data set and use them to describe how spread out the data is. 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
Data helps people make decisions. Students use these skills to read sports stats, compare survey results, notice patterns, and decide what a graph is really saying.
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 leer datos, hacer gráficas y explicar patrones. 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
Los datos ayudan a tomar decisiones. Su hijo/a aprende a leer gráficas, comparar resultados y explicar patrones.
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
The distance from the least value to the greatest value, found by subtracting: greatest − least.
Example: 30 − 12 = 18
One of the three values that cut an ordered data set into four equal-sized groups.
Example: Q1 = 9 for the lower half 4, 8, 10, 14
The distance across the middle half of the data, found by subtracting the first quartile from the third: Q3 − Q1.
Example: 88 − 75.5 = 12.5
How much the values in a data set differ from one another — whether they sit close together or far apart.
Example: Scores running from 68 to 94
A single number that describes the spread of a whole data set. The range and the IQR are both measures of variation.
Example: An IQR of 12.5
Try It Together
Pick one or two problems. Let your child explain the first step before opening the answer.
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Find the mean of 4, 6, 8, and 10.
Show answer
7
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Find the median of 3, 5, 9, 12, and 20.
Show answer
9
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A dot plot has four dots above 6. What does that mean?
Show answer
The value 6 appears four times.
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Name one question data could help answer.
Show answer
Answers vary, such as which lunch is most popular.