Ms. Jennifer DeBlois

This week, we’re learning to solve one-step word problems using multiplication and division. Students and families can do an interactive math activity and video (Lesson #11: Solve One-Step Word Problems) to practice what we’re learning in class.

• If we know the number of groups/rows and the number in each group/row, then we need to multiply to find the total.
• If we know the total and are missing either the number of groups/rows or the number in each group/row, then we need to divide.
• We’ll also be learning to use a variable (letter) in place of a blank or question mark when solving equations.

Example: Mike walks 3 miles each day for 5 days. How many total miles does Mike walk?

• We know the number of days and the number of miles per day. We do not know the total, so we want to multiply.
• 5 x 3 = m
• m = 15. Mike walks 15 miles total.

Example: Jennifer has 24 pages to read in a book. She reads 6 pages each day. How many days does it take her to read the book?

• We know the total number of pages and the number of pages per day. We do not know the number of days, so we want to divide.
• 24 ÷ 6 = p
• We can also think p x 6 = 24.
• p = 4. It takes Jennifer 4 days to read the book.

Students will also write word problems based on a given picture. When writing a word problem, you have to give two pieces of information and then ask a question to be solved. In class, we’ve been saying, “Tell. Tell. Ask.”

Example: Write a word problem about the picture.

• *******
• *******
• *******

There are 3 vases. Each vase has 7 flowers in it. How many total flowers are there?

OR

There are 21 people on the track team. 7 players ride in each van to get to the track meet. How many vans are there?

OR

Bethany has 21 books to put equally onto 3 shelves. How many books will be on each shelf?

Students will have math homework on Tuesday, Wednesday, Thursday, and Friday this week.

The week before Winter Break, we worked on using place value to multiply. Students and families can do an interactive math activity and video (Lesson #10: Multiply by Multiples of 10) to practice what we learned in class. An additional interactive video is available for this skill too.

• Multiply Multiples of 10

We used the Distributive Property (learned earlier this year) to decompose larger numbers into smaller ones to make multiplying easier.

Example:

• 16 x 10 =
• Decompose the 16 into 10 + 6.
• Now we have (10 + 6) x 10.
• Multiply each number in parentheses by 10.
  • (10 x 10) + (6 x 10)
  • 100 + 60 = 160

We also learned that we can apply the Associative Property (also learned earlier this year) to reorder the numbers to make multiplying easier.

Example:

• 6 x 90 =
• Decompose the 90 into 9 x 10.
• Now we have 6 x (9 x 10).
• Move the parentheses to (6 x 9) x 10 in order to get a basic “Rocket Math Fact” and in order to be able to multiple by 10.
• Now we have (6 x 9) x 10.
  • 54 x 10 = 540

We also learned a couple of “shortcuts,” but not before understanding the meaning of what we’re doing. These “shortcuts” are only helpful if you have good mastery of your basic multiplication facts. Mastering your basic math facts and knowing them by heart is so important because it helps make other areas of learning in math so much smoother.

• When we multiply by 10, we add a zero to the end of the other number and we get our answer.
  • 16 x 10 = 160
  • 54 x 10 = 540
  • 10 x 76 = 760
• When we multiple a single digit by a multiple of 10, look for the basic “Rocket Math Fact” inside of the problem. Find the answer to the basic “Rocket Math Fact” and then add a zero to the end.
  • 6 x 90 = 540
  • 60 x 4 = 240
  • 30 x 9 = 270

The last two weeks, we worked on adding and subtracting using place value. Students and families can do an interactive math activity and video (Lesson #9: Use Place Value to Add and Subtract) to practice what we learned in class. Additional interactive videos are available for this skill too.

• Use Hundreds, Tens, and Ones
• Add Three-Digit Numbers
• Add Within 1,000 on Number Lines
• Subtract Three-Digit Numbers
• Subtract Within 1,000 on Number Lines

Adding

We can take the numbers from standard form and put them into expanded form. Next, add the ones (7+2), the tens (40+70), and the hundreds (100+200). Finally, put those answers into standard form (300+110+9=419)

•    147         100 + 40 + 7
• + 272      + 200 + 70 + 2
•  ———       ————————
•                  300 + 110  + 9 = 419

We can also use unit form to add.

•    147
• + 272
•  ———
•        9  Add the ones. (7 ones + 2 ones = 9 ones, or 9)
•    110  Add the tens. (4 tens + 7 tens = 11 tens, or 1 hundred + 1 ten, or 110)
•    300  Add the hundreds. (1 hundred + 2 hundreds = 3 hundreds, or 300)
• ———-
•    419  Add them all together.

We can also use the traditional method of regrouping (carrying).

•    1
•    147
• + 272
•  ———
•    419

Subtracting

We can take the numbers from standard form and put them into expanded form. Next, subtract the ones (8-6). Then subtract the tens. We can’t do 60-80, so we trade first. Take 1 hundred away from the hundreds place and give it to the tens place. We now have 16 tens, or 160. (160-80). Now, subtract the hundreds (200-100). Finally, put those answers into standard form (100+80+2=182) *Sorry that I can’t show crossing out numbers to regroup on this post.

•                  200   160
•    368         300 + 60 + 8
• – 186      – 100 + 80 + 6
•  ———       ————————
•                  100 + 80  + 2 = 182

We can also add on to subtract. Begin at 186 and count up to 368. Start at 186. It’s 4 jumps of 1 on a number line to get to 190. It’s 1 jump of 10 to get to 200. It’s 1 jump of 100 to get to 300. It’s 6 jumps of 10, or 60, to get to 360. It’s 8 jumps of 1 to get to 368. Combine the jumps: 4 + 10 + 100 + 60 + 8 = 182.

•    368
• – 186
•  ————-

We can also use the traditional method of regrouping (borrowing). *Sorry that I can’t show crossing out numbers to regroup on this post.

•    2  16
•    3  6  8
• – 1  8  6
•  ————-
•    1  8  2