This question tests 1st grade ability to mentally find 10 more or 10 less than a two-digit number (CCSS.1.NBT.C.5). To add or subtract 10 mentally, use place value understanding: since 10 equals 1 ten and 0 ones, subtracting 10 means removing 1 ten (tens digit decreases by 1), while the ones digit stays the same. For example, $38 - 10 = 28$ because $3$ tens $- 1$ ten $= 2$ tens, and the 8 ones remain unchanged. The scenario involves Keisha having 38 marbles and giving away 10, requiring finding 10 less than 38. Choice B is correct because subtracting 10 from 38 means removing 1 ten: $3$ tens $- 1$ ten $= 2$ tens, ones stay 8, giving 28. Choice A is a common error where students subtract too much, like subtracting 20 to get 18; this happens because counting by ones is a fallback that can lead to errors when they miscount. To help students: Use base-10 blocks to show physically removing 1 ten-rod while ones stay constant; practice on hundred charts (subtract 10 = up one row); emphasize pattern 'tens change by 1, ones stay same'; provide many examples showing ones digit constant; connect to skip counting by 10s; use number lines with jumps of 10; practice mental math daily with quick '10 less' questions; explain why this is efficient compared to counting by ones; make the place value connection explicit.

This question tests 1st grade ability to mentally find 10 more or 10 less than a two-digit number (CCSS.1.NBT.C.5). To add or subtract 10 mentally, use place value understanding: since 10 equals 1 ten and 0 ones, adding 10 means adding 1 ten (so the tens digit increases by 1), while the ones digit stays the same. For example, 47 + 10 = 57 because 4 tens + 1 ten = 5 tens, and the 7 ones remain unchanged. The scenario involves Maya using base-10 blocks for 4 tens and 7 ones, then adding 1 ten. Choice B is correct because adding 1 ten to 4 tens and 7 ones gives 5 tens and 7 ones, which is 57. Choice C is a common error where students don't change the tens digit and keep the original number 47; this happens because the connection between adding a ten-rod and updating the tens place isn't automatic yet. To help students: Use base-10 blocks to show physically adding 1 ten-rod while ones stay constant; practice on hundred charts (add 10 = down one row); emphasize pattern 'tens change by 1, ones stay same'; provide many examples showing ones digit constant; connect to skip counting by 10s; use number lines with jumps of 10; practice mental math daily with quick '10 more' questions; explain why this is efficient compared to counting by ones; make the place value connection explicit.

This question tests 1st grade ability to mentally find 10 more or 10 less than a two-digit number (CCSS.1.NBT.C.5). To add or subtract 10 mentally, use place value understanding: since 10 equals 1 ten and 0 ones, subtracting 10 means removing 1 ten (tens digit decreases by 1), while the ones digit stays the same. For example, 45 - 10 = 35 because 4 tens - 1 ten = 3 tens, and the 5 ones remain unchanged. The scenario involves finding 45 - 10 mentally, with a hint that only the tens digit changes. Choice C is correct because subtracting 10 from 45 means removing 1 ten: 4 tens - 1 ten = 3 tens, ones stay 5, giving 35. Choice A is a common error where students add 10 instead of subtracting, resulting in 55; this happens because they reverse the operation, perhaps misreading the subtraction sign. To help students: Use base-10 blocks to show physically removing 1 ten-rod while ones stay constant; practice on hundred charts (subtract 10 = up one row); emphasize pattern 'tens change by 1, ones stay same'; provide many examples showing ones digit constant; connect to skip counting by 10s; use number lines with jumps of 10; practice mental math daily with quick '10 less' questions; explain why this is efficient compared to counting by ones; make the place value connection explicit.

This question tests 1st grade ability to mentally find 10 more or 10 less than a two-digit number (CCSS.1.NBT.C.5). To add or subtract 10 mentally, use place value understanding: since 10 equals 1 ten and 0 ones, adding 10 means adding 1 ten (so the tens digit increases by 1), while the ones digit stays the same. For example, 34 + 10 = 44 because 3 tens + 1 ten = 4 tens, and the 4 ones remain unchanged; similarly, subtracting 10 means removing 1 ten (tens digit decreases by 1), while ones stay the same: 67 - 10 = 57 because 6 tens - 1 ten = 5 tens, and the 7 ones remain unchanged. The question asks to find 10 less than 82, noting tens change by 1 while ones stay the same. Choice A is correct because subtracting 10 from 82 means removing 1 ten: 8 tens - 1 ten = 7 tens, ones stay 2, giving 72. Choice B is a common error where students subtract 1 from the ones digit instead, resulting in 81; this happens because students sometimes focus on the digit '10' rather than its place value meaning. To help students: Use base-10 blocks to show physically removing 1 ten-rod while ones stay constant; practice on hundred charts (subtract 10 = up one row); emphasize pattern 'tens change by 1, ones stay same'; provide many examples showing ones digit constant; connect to skip counting by 10s; use number lines with jumps of 10; practice mental math daily with quick '10 less' questions; explain why this is efficient compared to counting by ones; make the place value connection explicit.

This question tests 1st grade ability to mentally find 10 more or 10 less than a two-digit number (CCSS.1.NBT.C.5). To add or subtract 10 mentally, use place value understanding: since 10 equals 1 ten and 0 ones, adding 10 means adding 1 ten (so the tens digit increases by 1), while the ones digit stays the same. For example, 34 + 10 = 44 because 3 tens + 1 ten = 4 tens, and the 4 ones remain unchanged. The scenario involves Emma starting with 34 stickers and getting 10 more, requiring mental addition of 10 to 34. Choice A is correct because adding 10 to 34 means adding 1 ten: 3 tens + 1 ten = 4 tens, ones stay 4, giving 44. Choice B is a common error where students add 1 instead of 10, resulting in 35; this happens because understanding 10 as 1 ten is abstract and students sometimes focus on the digit '1' rather than its place value meaning. To help students: Use base-10 blocks to show physically adding 1 ten-rod while ones stay constant; practice on hundred charts (add 10 = down one row); emphasize pattern 'tens change by 1, ones stay same'; provide many examples showing ones digit constant; connect to skip counting by 10s; use number lines with jumps of 10; practice mental math daily with quick '10 more' questions; explain why this is efficient compared to counting by ones; make the place value connection explicit.

Maya starts with 23 stickers. After giving away 10, she has 23 - 10 = 13. Then she finds 10 more: 13 + 10 = 23. She ends up with the same amount she started with. Choice A shows only the first step. Choice C incorrectly adds 10 to the starting amount. Choice D incorrectly adds 20 to the starting amount.

If Tom's number plus 10 equals 65, then Tom's number is 65 - 10 = 55. We can check: 55 + 10 = 65 ✓. Choice A incorrectly adds 10 to 65. Choice B subtracts 1 instead of 10. Choice D adds 1 instead of subtracting 10.

Ben is adding 10 each time: 29 + 10 = 39, then 39 + 10 = 49, so 49 + 10 = 59. When adding 10, only the tens digit changes (from 4 to 5), while the ones digit stays 9. Choice A adds 1 instead of 10. Choice B doesn't follow the pattern of adding 10. Choice D subtracts instead of adding.

To find 10 less than 53, subtract 10: 53 - 10 = 43. Emma is correct. Jake subtracted 1 instead of 10, which gives 1 less, not 10 less. Choice A explains Jake's error but says he's correct. Choice C gives 10 more instead of 10 less. Choice D is incorrect because only one answer can be right.

This is a multi-step word problem that requires you to track changes to Lisa's collection of books. When you see problems with multiple operations, work through them step by step in the order they happen.

Start with Lisa's original amount: $$32$$ books. First, she gets $$10$$ more books for her birthday, so you add: $$32 + 10 = 42$$ books. Next, she gives $$20$$ books to the library, so you subtract: $$42 - 20 = 22$$ books. Lisa ends up with $$22$$ books after all the changes.

Looking at the wrong answers: Choice B ($$12$$ books) happens if you subtract both the birthday books and library books from the original amount: $$32 - 10 - 20 = 2$$, or if you make an error in your final subtraction. Choice C ($$42$$ books) is the amount Lisa had after getting birthday books but before giving any to the library—this happens when you forget the final step. Choice D ($$62$$ books) occurs if you add all the numbers together instead of following the story: $$32 + 10 + 20 = 62$$.

The correct answer is A.

For multi-step word problems, always follow the story in order and keep track of your running total after each operation. Circle or underline key words like "gets" (addition) and "gives away" (subtraction) to help you identify which operation to use at each step.