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Math for Grade 2
1 Number Sense and Numeration
1-1 Counting
1-1 1 Count forward from any given number up to 100
1-1 2 Count backward from any given number within 100
1-2 Place Value
1-2 1 Understand the concept of tens and ones
1-2 2 Identify the place value of digits in two-digit numbers
1-3 Comparing Numbers
1-3 1 Compare two-digit numbers using symbols (<, >, =)
1-3 2 Order numbers from least to greatest and greatest to least
1-4 Rounding
1-4 1 Round numbers to the nearest ten
2 Addition and Subtraction
2-1 Basic Addition
2-1 1 Add two one-digit numbers
2-1 2 Add a one-digit number to a two-digit number
2-2 Basic Subtraction
2-2 1 Subtract two one-digit numbers
2-2 2 Subtract a one-digit number from a two-digit number
2-3 Addition and Subtraction Facts
2-3 1 Memorize addition facts for sums up to 20
2-3 2 Memorize subtraction facts for differences up to 20
2-4 Word Problems
2-4 1 Solve addition word problems with two-digit numbers
2-4 2 Solve subtraction word problems with two-digit numbers
3 Measurement and Data
3-1 Length
3-1 1 Compare the lengths of objects using non-standard units
3-1 2 Measure the lengths of objects using standard units (centimeters and meters)
3-2 Time
3-2 1 Tell time to the nearest hour and half-hour
3-2 2 Understand the concept of A M and P M
3-3 Data Collection
3-3 1 Collect and organize data in a simple bar graph
3-3 2 Interpret data from a simple bar graph
4 Geometry
4-1 Shapes
4-1 1 Identify and name basic 2D shapes (circle, square, triangle, rectangle)
4-1 2 Identify and name basic 3D shapes (cube, sphere, cone, cylinder)
4-2 Spatial Relationships
4-2 1 Understand and use positional words (above, below, beside, between, etc )
4-2 2 Understand and use directional words (left, right, forward, backward)
5 Patterns and Algebra
5-1 Patterns
5-1 1 Identify and extend simple patterns (AB, ABB, etc )
5-1 2 Create and describe patterns using shapes, colors, and numbers
5-2 Algebraic Thinking
5-2 1 Understand the concept of equality (e g , 3 + 2 = 5)
5-2 2 Use variables to represent unknown numbers in simple equations
1-4 Rounding

1-4 Rounding

Rounding is a mathematical technique used to simplify numbers by reducing their precision. This is particularly useful when dealing with large numbers or when an exact number is not necessary. In Grade 2, we focus on rounding numbers to the nearest ten.

Key Concepts

1. Rounding to the Nearest Ten

Rounding to the nearest ten means finding the multiple of ten that is closest to the given number. For example, rounding 47 to the nearest ten would result in 50 because 47 is closer to 50 than to 40.

2. Understanding the Midpoint

The midpoint between two tens is the number that is halfway between them. For instance, the midpoint between 40 and 50 is 45. If a number is exactly at the midpoint, it is typically rounded up to the higher ten.

3. Rules for Rounding

To round a number to the nearest ten:

Examples

Example 1: Rounding 34 to the Nearest Ten

The ones digit of 34 is 4. Since 4 is less than 5, we round down to the previous ten. Therefore, 34 rounded to the nearest ten is 30.

Example 2: Rounding 78 to the Nearest Ten

The ones digit of 78 is 8. Since 8 is 5 or more, we round up to the next ten. Therefore, 78 rounded to the nearest ten is 80.

Example 3: Rounding 45 to the Nearest Ten

The ones digit of 45 is 5. Since 5 is exactly at the midpoint, we round up to the next ten. Therefore, 45 rounded to the nearest ten is 50.

Analogies

Analogy 1: Like a Game of Hopscotch

Think of rounding as playing hopscotch. When you hop to a number that is close to a line, you decide whether to hop back or forward to the nearest line. If you are closer to the next line, you hop forward; if you are closer to the previous line, you hop back.

Analogy 2: Like a Balance Scale

Imagine a balance scale with two tens on either side. If you place a number on the scale, it will tilt towards the nearest ten. If the number is exactly in the middle, the scale might tilt slightly towards the higher ten.

By mastering the concept of rounding, you can simplify numbers and make calculations easier, which is a valuable skill for solving more complex math problems in the future.

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