Day 2 Presentation

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Math Foundations: Unit 1

Day 2: Estimation & Rounding

Today's Objectives

Warm-Up: Number Talk

In your head, what's a quick and easy way to solve this?

99 + 35

Did you use a "friendlier" number like 100? That's the basic idea of estimation!

What is Estimation?

Estimation is your math superpower!

It's a way to make a quick, smart guess *before* you do the exact math. This helps you know if your final answer makes sense.

The main tool we use for estimation is Rounding.

How to Round Numbers

The rule is simple:

4 or Less, Let it Rest

If the digit is 0, 1, 2, 3, or 4, the number you're rounding to stays the same.

32 ➔ 30

5 or More, Raise the Score

If the digit is 5, 6, 7, 8, or 9, you round the number up.

37 ➔ 40

The 3-Step Process

Let's solve: You have $48 and spend $29. About how much is left?

1. Estimate: Round first. $48 is about $50. $29 is about $30. So, 50 - 30 = 20.

2. Calculate: Find the exact answer. 48 - 29 = 19.

3. Compare: Is our exact answer (19) close to our estimate (20)? Yes! We can be confident.

Let's Practice Together

You are buying groceries that cost $12.25 and $6.99. Use the 3 steps.

1. Estimate: $12.25 is about $12. $6.99 is about $7. So, $12 + $7 = $19.

2. Calculate: $12.25 + $6.99 = $19.24.

3. Compare: Our estimate of $19 is very close to $19.24. Perfect!

Independent Practice

RED

Round to the nearest ten:

  1. 48
  2. 91
  3. 25

YELLOW

Estimate the sum by rounding to the nearest ten:

  1. 67 + 22
  2. 95 + 48

GREEN

Use the 3-Step Process for 152 - 39.

  1. Estimate (round to nearest ten)
  2. Calculate
  3. Compare

Exit Ticket

You drive 108 miles on Monday and 295 miles on Tuesday.
Estimate your total miles.

(Round to the nearest hundred first!)

1 / 9

Day 2 Notes: Estimation & Rounding

The Big Idea: Estimation is a Smart Guess

Estimation helps you know if your final answer is reasonable. The main tool we use for estimation is rounding.

The rule for rounding is: 5 or more, . 4 or less, .

The 3-Step Process for Solving Problems

Example Problem: You have $48 and spend $29. About how much is left?

1. Estimate: Round the numbers first, then solve.
- =

2. Calculate: Find the exact answer.
48 - 29 =

3. Compare: Is your exact answer close to your estimate? (Yes / No)

Practice Problem

You are buying groceries that cost $12.25 and $6.99. Use the three steps to find the total.

1. Estimate:

2. Calculate:

3. Compare: Are your answers close?

Exit Ticket

You drive 108 miles on Monday and 295 miles on Tuesday. Estimate your total miles by rounding to the nearest hundred first.

My Estimate: