Week 4 of 8
Week 4
2nd Grade → 3rd Grade · Addition regrouping 100 and Contractions
Math
Addition With Regrouping to 100
Two-digit addition where the ones column crosses ten — 47 + 38. Middle of second grade. CCSS 2.NBT.B.5 expects fluency by year's end.
The mistake to watch for. Writing the full two-digit sum in the ones column: 47 + 38 written as 715, because 7 + 8 = 15 goes in whole.
How to help. Ask "how many tens, how many ones?" for every sum over nine. Fifteen is one ten and five — the ten moves next door.
A worked example
Try 47 + 38. Ones: 7 + 8 = 15, so write 5 and carry 1 ten. Tens: 4 + 3 + 1 = 8. The answer is 85.
All addition with regrouping to 100 sets, with answer keys →
Reading & language
Contractions
Combining two words into one shorter word using an apostrophe in place of missing letters. Second grade.
The mistake to watch for. Putting the apostrophe in the wrong spot — writing "don't" as "do'nt", placing it where the words originally joined rather than where letters were dropped.
How to help. Have your child cross out exactly the letters the apostrophe replaces in the original two words ("do not" → the o in "not" is dropped) before writing the contraction.
A worked example
A contraction squeezes two words into one, and an apostrophe takes the place of the missing letters. 'Did not' becomes 'didn't' — the apostrophe stands in for the o.
Words for this week
- regroup
- To trade 10 ones for 1 ten (or 1 ten for 10 ones) when you add or subtract.
- carry
- To move extra tens (or hundreds) to the next column when you add.
- sum
- The answer you get when you add.
- ten
- The number 10, one more than nine.
- digit
- One of the ten number symbols 0 to 9. The number 47 has two digits.
- contraction
- Two words squeezed into one with an apostrophe, like don't for do not.
- apostrophe
- The little mark ( ' ) that shows letters are missing in a contraction, or that something belongs to someone.
- letter
- One of the symbols we use to write words, like a, b or c.
- word
- A group of letters that has a meaning.
Read this week
Greenland
A short earth & weather article from our Learn library, chosen for this reading level. Read it together, then ask your child to tell you one new thing they learned.