Mathematics Grade 5 15 min

Combinations

Combinations

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Introduction & Learning Objectives

Learning Objectives Define what a combination is in simple terms. Identify situations where the order of selection does not matter. Systematically list all possible combinations for a small set of items. Solve simple real-world problems involving combinations by listing or drawing. Explain why different arrangements of the same items are considered one combination. Distinguish between choosing items where order matters and where it does not (implicitly). Have you ever had to choose a few snacks from a bigger basket? 🍎🍪🥨 What if it doesn't matter which snack you pick first? 🤔 In this lesson, you'll learn about 'combinations,' which are ways to choose items where the order you pick them in doesn't change the group. Understanding combinations helps...
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Key Concepts & Vocabulary

TermDefinitionExample CombinationA combination is a way of choosing items from a larger group where the order of the items does NOT matter. It's about the group you end up with, not how you got them.If you choose an apple and then a banana, it's the same combination as choosing a banana and then an apple. You still have an apple and a banana. SetA set is a collection of distinct items or objects. Think of it as a group of things you can choose from.The set of fruits {apple, banana, orange}. Element (or Item)An element is a single item or object within a set.In the set {red, blue, green}, 'red' is an element. SelectionSelection is the act of choosing one or more items from a larger set.If you have 5 crayons and you pick 2, that's a selection. Systematic ListingSyst...
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Core Formulas

The 'Order Doesn't Matter' Rule When forming a group of items, if changing the sequence of the items within that group does not create a new group, then it is a combination problem. This rule helps you decide if you're looking for combinations. For example, if you're choosing two colors for a painting, 'red and blue' is the same group of colors as 'blue and red'. The 'Systematic Listing' Rule To find all possible combinations, list them in an organized way (e.g., always starting with the first item, then the second, and so on) to ensure every unique group is found exactly once. This rule helps you be thorough and accurate. For instance, if choosing 2 fruits from {apple, banana, cherry}, start with apple: (apple, banana),...

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Sample Practice Questions

Challenging
You have 5 friends and can invite 3 to the movies. The number of ways to choose 3 friends to invite is the same as the number of ways to choose which friends to NOT invite. How many friends are you choosing to NOT invite?
A.3
B.5
C.1
D.2
Challenging
There are 6 colored blocks in a bag: Red, Blue, Green, Yellow, Orange, Purple. How many different combinations of 2 blocks can you pull out?
A.15
B.30
C.12
D.6
Challenging
A student correctly found there are 6 combinations when choosing 2 items from a set of 4. If they add a 5th item to the set, how many *total* combinations of 2 items are now possible?
A.7
B.24
C.10
D.8

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