Standard Units

Grade 2 · measurement · 109 practice problems · read aloud

🔊 Listen to this explanation

📏 Standard Units: Measuring Made Easy

Standard units are the special rulers we all agree to use so we can measure things the same way! We use inches and feet for length. This helps us share and compare measurements with everyone.

How to Measure with a Ruler

  1. Line it up: Place the start of your ruler (the 0 mark) at one end of the object.
  2. Read the number: Look at the number on the ruler that lines up with the other end of the object.
  3. Say the unit: Don't forget to say if it's inches or feet!

Let's Look at Some Examples

Example 1: Measuring a Crayon

A crayon is lined up with a ruler. One end is at 0, and the other end is at the number 4. The crayon is 4 inches long.

Example 2: Measuring a Book

A book is 1 foot long. We know that 1 foot is the same as 12 inches. So, the book is also 12 inches long.

⚠️ Common Mistakes to Avoid

Starting at the wrong spot: Don't start measuring from the end of the ruler! Always find the 0 mark first.

Forgetting the unit: Saying "The pencil is 6" doesn't help. Always say "6 inches" or "6 feet".

💡 Tips & Tricks

Body Benchmarks: Your thumb is about 1 inch wide. Your foot is about 1 foot long! Use these to make a good guess.

Inches vs. Feet: Inches are for smaller things (crayons, erasers). Feet are for bigger things (desks, doors).

How to Practice

  • Go on a measurement hunt! Find 5 things in your room that are longer than a foot and 5 things that are shorter.
  • Use a ruler to measure your favorite toys. How many inches long is your toy car or doll?
  • Draw a line that is 5 inches long. Then, draw a line that is 1 foot long.

Practice problems

6 of the 109, worked through step by step — try them before opening the answer.

1 24 + 37 = ?

Hint: Think about adding the tens first, then the ones, and combining them.

Show the answer

Answer: 61

  1. Write the numbers vertically in your mind (or on paper) to align by place value: 24 + 37
  2. Add the digits in the ones column first (rightmost column). Ones column: 4 + 7 = 11. 11 is a two-digit number, so we split it into 1 ten and 1 one.
  3. Write down the 1 in the ones place of the answer, and carry over the 1 ten to the tens column.
  4. Now add the tens column: Tens column: 2 + 3 = 5, plus the carried-over 1 makes 5 + 1 = 6.
  5. Combine the tens and ones: Tens digit is 6, ones digit is 1, so the result is 61. Final answer: 61

We are adding 24 and 37.

2 56 + 38 = ?

Hint: Add the ones place first, then add the tens place. Remember to regroup if needed.

Show the answer

Answer: 94

  1. Add the ones place: 6 + 8 = 14. Write down 4 in the ones place and carry over 1 to the tens place.
  2. Add the tens place: 5 + 3 = 8, plus the carried over 1 makes 9.
  3. Combine the tens and ones: 90 + 4 = 94.

The answer is 94.

3 74 - 29 = ?

Hint: Think about regrouping when subtracting. Start from the ones place.

Show the answer

Answer: 45

  1. Look at the ones place: 4 - 9. Since 4 is smaller than 9, we need to regroup from the tens place.
  2. Take 1 ten from 7 tens, which leaves 6 tens. The 1 ten becomes 10 ones, so now we have 14 ones (10 + 4).
  3. Subtract the ones: 14 - 9 = 5
  4. Subtract the tens: 6 - 2 = 4
  5. Combine the results: 45

The answer is 45.

4 74 - 28 = ?

Hint: Remember to regroup when subtracting the ones place

Show the answer

Answer: 46

  1. Write the problem vertically 74 - 28
  2. Look at the ones place: 4 - 8 Since 4 is smaller than 8, we need to regroup
  3. Take 1 ten from the tens place (7 becomes 6) Add 10 to the ones place (4 becomes 14)
  4. Now subtract the ones place: 14 - 8 = 6
  5. Subtract the tens place: 6 - 2 = 4
  6. Combine the results: 46

The answer is 46.

5 A tree is 145 cm tall and a bush is 78 cm tall. How much taller is the tree?

Hint: Think about which operation helps you find the difference between two measurements.

Show the answer

Answer: 67

  1. Identify the heights: tree = 145 cm, bush = 78 cm.
  2. Subtract the bush's height from the tree's height: 145 - 78.
  3. Subtract the ones place: 5 - 8. Since 5 is smaller than 8, regroup 1 ten from the tens place. 4 tens become 3 tens, and 5 ones become 15 ones.
  4. Now subtract the ones: 15 - 8 = 7.
  5. Subtract the tens place: 3 - 7. Since 3 is smaller than 7, regroup 1 hundred from the hundreds place. 1 hundred becomes 0 hundreds, and 3 tens become 13 tens.
  6. Now subtract the tens: 13 - 7 = 6.
  7. The hundreds place: 0 - 0 = 0.
  8. Combine the results: 60 + 7 = 67. The tree is 67 centimeters taller than the bush.

6 A bookshelf is 92 cm tall and a desk is 65 cm tall. How much taller is the bookshelf?

Hint: Think about which operation helps you find the difference between two measurements.

Show the answer

Answer: 27

  1. Identify the heights: bookshelf = 92 cm, desk = 65 cm.
  2. Subtract the desk's height from the bookshelf's height: 92 - 65.
  3. Subtract the ones place: 2 - 5. Since 2 is smaller than 5, regroup 1 ten from the tens place. 9 tens become 8 tens, and 2 ones become 12 ones.
  4. Now subtract the ones: 12 - 5 = 7.
  5. Subtract the tens: 8 - 6 = 2.
  6. Combine the results: 20 + 7 = 27. The bookshelf is 27 centimeters taller than the desk.
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