Unit 10: Patterns, Sequences, and Early Algebraic Thinking

Day 27 of 30

Use function machines

K-2Mathematics

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Learning Objective

I can use function machines.

Today's Lesson

Today we will learn how to use function machines. Math helps us solve problems and understand the world around us.

A function is a relationship where each input has exactly one output. Think of it as a machine: you put in a value (input/x), it processes it with a rule, and gives back one result (output/y). Function notation: f(x) means "function f at x." For example, if f(x) = 2x + 3, then f(5) = 2(5) + 3 = 13. Functions model relationships in the world: temperature over time, cost based on quantity, distance from speed. Every function has a domain (allowed inputs) and range (possible outputs). Functions are fundamental to mathematics!

Let's break this down step by step so it's easy to understand. Follow along with the examples, and don't worry if it takes some practice to get the hang of it!

Remember: Making mistakes is part of learning. If something is tricky, try again, look at the examples, or ask for help.

Key Terms
Problem

A question we need to solve

Solution

The answer to a problem

Activities
Instructions
1. Use objects or pictures to explore use function machines. 2. Try the examples together. 3. Solve practice problems. 4. Check your work.
Materials Needed
  • Counters or objects
  • Pencil
  • Practice sheet
Practice Problems
1

If f(x) = 3x + 2, find f(4)

Hint: Substitute 4 for x.
2

Is the relation {(1,2), (2,3), (1,4)} a function?

Hint: Check if any x-value repeats with different y.
3

If f(x) = x² - 1, find f(-2)

Hint: Substitute -2 for x. Remember (-2)² = 4.

Teaching Tip

For younger learners: Use concrete objects and hands-on activities when teaching use function machines. Keep sessions short (10-15 minutes) and incorporate movement or songs when possible.

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