Place value: The value of a digit based on its position in a number
Note: In grade 1, we focus on ones and tens places.
- Identify each digit in the number
- Determine the position of each digit (rightmost is ones, next is tens)
- State the value of each digit based on its position
The number 37 has two digits: 3 and 7
7 is in the ones place, 3 is in the tens place
3 in tens place = 3 × 10 = 30; 7 in ones place = 7 × 1 = 7
3 tens and 7 ones
• Position matters: Each position represents a different value
• Rightmost digit: Always in the ones place
• Next position: Tens place (10 times the digit)
• Practice Tip: Count by tens and ones to verify place values
- 45 = 4 tens + 5 ones - Practice with different numbers
- 28 = 2 tens + 8 ones - Practice with smaller tens digit
- 61 = 6 tens + 1 one - Practice with different combinations
- Think of tens as groups of 10, ones as individual units
- Count by tens: 10, 20, 30... to understand the tens place
- Remember: 37 means 3 groups of 10 plus 7 extra ones
Q: How do I know which digit is in the tens place?
A: The tens place is the second digit from the right. In 37, the 3 is in the tens place.
Q: Why is place value important?
A: It helps us understand the actual value of each digit in a number and compare numbers.
Number representation: Using base ten blocks to show the place value composition of a number
Note: Rods represent tens, cubes represent ones.
- Identify the tens digit in the number
- Use that many rods (long blocks)
- Identify the ones digit in the number
- Use that many cubes (small blocks)
42 = 4 tens + 2 ones
4 tens = 4 rods (each rod represents 10)
2 ones = 2 cubes (each cube represents 1)
4 rods + 2 cubes = 42
4 rods and 2 cubes
• Rod assignment: Each rod represents 10 units
• Cube assignment: Each cube represents 1 unit
• Place value connection: Tens digit → rods, ones digit → cubes
• Practice Tip: Use physical blocks to verify your representation
- 35 = 3 rods + 5 cubes - Practice with different numbers
- 58 = 5 rods + 8 cubes - Practice with larger tens digit
- 19 = 1 rod + 9 cubes - Practice with smaller tens digit
- Rods represent the tens place digit
- Cubes represent the ones place digit
- Count by tens for rods, then add ones
Q: Can I represent a number with only cubes?
A: Yes, but using the correct combination of rods and cubes is more efficient and helps understand place value.
Q: How do I know if my representation is correct?
A: Count the total value of your blocks to verify it matches the target number.
Number comparison: Using place value to determine which number is larger or smaller
Note: Compare digits starting from the highest place value (leftmost).
- Compare the tens digits first
- If tens are equal, compare the ones digits
- Determine which number is greater based on the comparison
53 has 5 tens, 48 has 4 tens. Since 5 > 4, 53 > 48
Since tens are different, ones digits don't affect the comparison
53 is greater than 48 because it has more tens
53 is greater than 48 because 53 has 5 tens while 48 has only 4 tens
• Start left: Always compare from the highest place value first
• Tens matter more: A number with more tens is always greater
• Only compare ones if tens are equal: Focus on the highest differing place value
• Practice Tip: Think of tens as groups of 10 objects to visualize the difference
- 64 vs 57 → 64 > 57 (6 tens > 5 tens)
- 42 vs 48 → 48 > 42 (equal tens, 8 ones > 2 ones)
- 71 vs 65 → 71 > 65 (7 tens > 6 tens)
- Always start comparing from the leftmost digit
- If tens are the same, compare the ones digits
- More tens always means a greater number
Q: What if both numbers have the same tens digit?
A: Then compare the ones digits. The number with more ones is greater.
Q: Why do we start comparing from the left?
A: Because the leftmost digits have the greatest place value and determine the overall size.
Ascending order: Arranging numbers from smallest to largest (least to greatest)
Note: Use place value to compare numbers systematically.
- Compare tens digits first to group numbers
- Within each group, compare ones digits from smallest to largest
- Arrange from smallest to largest
Numbers with 1 ten: 18; Numbers with 2 tens: 21, 25; Numbers with 3 tens: 32
For 2 tens: 21 < 25 (1 one < 5 ones)
18 (1 ten), then 21, 25 (both 2 tens), then 32 (3 tens)
18, 21, 25, 32
• Group by tens: Numbers with fewer tens come first
• Within groups: Compare ones digits when tens are equal
• Systematic approach: Organize numbers by tens, then by ones
• Practice Tip: Use place value breakdown to make comparisons clearer
- 34, 28, 37, 25 → 25, 28, 34, 37 (group by tens first)
- 41, 38, 46, 33 → 33, 38, 41, 46 (3 tens first, then 4 tens)
- 52, 49, 56, 43 → 43, 49, 52, 56 (order by tens, then by ones)
- Start by grouping numbers with the same tens digit
- Within each group, order by ones digits
- Remember: numbers with fewer tens always come before numbers with more tens
Q: What if I have many numbers to order?
A: Group them by tens first, then order within each group by ones digits.
Q: Can I order them randomly?
A: No, use place value systematically to ensure correct order.
Block interpretation: Determining the number represented by given base ten blocks
Note: Each rod represents 10, each cube represents 1.
- Count the number of rods (tens)
- Multiply by 10 to get the tens value
- Count the number of cubes (ones)
- Add the tens and ones values together
4 rods = 4 × 10 = 40
6 cubes = 6 × 1 = 6
40 + 6 = 46
46
• Rod value: Each rod represents 10 units
• Cube value: Each cube represents 1 unit
• Place value addition: Tens + ones = the total number
• Practice Tip: Count by tens for rods, then count on for cubes
- 3 rods + 5 cubes = 35
- 2 rods + 8 cubes = 28
- 5 rods + 1 cube = 51
- Rods represent tens (multiply by 10)
- Cubes represent ones (count as single units)
- Add the tens and ones values together
Q: How do I calculate the value of rods?
A: Each rod represents 10, so multiply the number of rods by 10.
Q: What if I have more than 10 cubes?
A: 10 cubes can be traded for 1 rod. So 13 cubes would be 1 rod and 3 cubes.