Mr. Salsich's Class
Third Grade Explorations in Learning
Groups of Things
We are starting to learn about multiplication in math.
Multiplication is really just a faster way to add together equal groups of things. Here’s an example from Jennifer:
7 groups of 3
Here are 7 Pikachus.
Each Pikachu has 3 bowls of food.
Because each Pikachu (a type of Pokemon) has an equal number of bowls, we can say that this is 7 groups of 3. You can figure out how many bowls there are altogether by adding 3 together 7 times:
3 + 3 + 3 + 3 + 3 + 3 + 3 = 21
There are 21 bowls of food in all.
Multiplication makes it easier than adding up each 3. You can skip-count by the equal groups (3, 6, 9, 12, 15, 18, 21), or better still, memorize the multiplication facts. We also call multiplication “times” because you are adding the same number a certain amount of times. So, 7 groups of 3 also means:
7 x 3 = 21
Here are more examples of turning equal groups of things into multiplication:
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With multiplication you can quickly find the total amount of equal groups of things. We will use this a lot in math when we start doing serious skip counting, figuring out arrays, and then division.
Here is a multiplication picture-problem for you to solve:
20 groups of 10
Here are 20 wacky students.
Each wacky student has 10 fingers.
How many fingers are there in all?
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Can you solve the equal groups question above?
What did you think of our multiplication pictures and sentences?
Can you think of other problems from everyday life that we can use multiplication to solve?
52 Responses to “Groups of Things”
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January 17th, 2012 at 2:29 am
I actually am very taken by the delightful qualities of the art work, they’d make fabulous backgrounds as ‘greenscreens’! I spotted that one of Sophia’s ladybirds was an odd one out, but which one?
Maths in everyday life is something I use all the time. I’m having 4 friends to dinner on Saturday so there will be 6 of us all together. Everyone is having a date and pineapple dessert. Each person will have 4 or 5 large dates. To be safe how many dates will I need to buy?
Mr E
Hawes
January 18th, 2012 at 3:54 pm
Dear Mr. E,
I like how you leave math on blogs to help kids learn and for kids to have fun if they like math or just want to do it. This is how I got my answer.
5,10, 15, 20, 25, 30
5+5+5+5+5+5=30
The multiplication sentence is 6×5=30
Your friend,
Jackie
January 18th, 2012 at 4:00 pm
Dear Mr. E,
you should get 30 dates if you are going to have six people over and they are going to have five dates each you need to get 30 dates.
From,
Dylan
January 18th, 2012 at 4:02 pm
Dear Mr. E
Thank you for your awesome comment. Here is how I solved your question; I did 6+6+6+6+6 and and then added up two sixes and then another two so then 12 +12 + 6 and I figured out the sum is 30 so that is how many dates you need.
Your blogging buddy,
Luke
January 18th, 2012 at 4:03 pm
Dear Mr. E,
You will need 30 dates for your desserts. I did 6 x 5 to get 30. I also counted by 5′s to get the answer.
from,
Jennifer
January 18th, 2012 at 4:10 pm
Dear Mr. Eldridge,
I drew 6 plates and put 5 dots in each one. I counted 30 dots. My multiplication sentence is 6 times 5. You will need 30 dates.
You friend,
Joseph
January 17th, 2012 at 8:42 am
Dear Boys and Girls,
I loved your clever and creative artwork, and it was fun for me to see multiplication explained in such a clear and simple way. Congratulations on another learning job done very well!
Sincerely,
Mr. Hamilton Salsich
January 17th, 2012 at 11:10 pm
Dear Mr Salsich and class,
Wonderful Post I thought it was great!
Great job everyone for makeing great pictures and working out multiplucation sums.
I think multiplication is a good way to learn how to add things up quiker!
Yes I think i can add the multiplication sum up I think it is 20 students and 10 fingers each equals up to… drum roll please… 200. Well, thats what I think!
I think you guys might know me from Mrs Morris and Miss Jordan I was Mrs Morris’s student in 2010.
If you would like to stay in touch with me here is my blog address…
rhiannonb.global2.vic.edu.au/
You new blogging buddy,
Rhiannon
Australia
January 18th, 2012 at 4:35 am
Dear Mr Salsich and class
I think your pictures are great because they clearly show the problems you are trying to solve.
Here is a problem that I made up for the B4 children a couple of years ago:
There are 7 trees growing in a field.
When it rains, the dinosaurs hide under the trees.
Each tree can cover 5 dinosaurs.
How many dinosaurs can keep dry under trees?
best wishes
Mrs M♔Kenzie
January 18th, 2012 at 4:04 pm
Dear Mrs. Mckenzie,
I think I have the answer to your math problem. Is it 35? I’ll tell you how I got it. So I did 7×5. I counted 5 seven times and it got me to 35. That’s the times problem, now the repeated addition is 5+5+5+5+5+5+5=35
Brian G.
January 18th, 2012 at 4:06 pm
Dear Mrs.Mckenzie,
I like your question. The answer is 35. This is how I got it 5,10,15,20,25,30,35.
Your friend,
Chase
January 18th, 2012 at 4:07 pm
Dear Mrs McKenzie ,
5×7=35
I figured your problem out by skip counting by 5′s like this:
5, 10, 15, 20, 25, 30, 35.
So, 35 dinosaurs could stay dry under the trees.
From,
Carly
January 19th, 2012 at 2:42 am
Dear Carly, Chase and Brian
Thank you – you all solved the problem correctly, and between you used two different strategies – repeated addition and skip-counting.
It’s always handy to have more than one strategy to solve problems.
Here is another problem for you. I wonder what strategy you will use this time?
If there are 6 trees and 37 dinosaurs how many dinosaurs will stay wet?
from Mrs M♔Kenzie
January 18th, 2012 at 3:54 pm
Dear Mr. Salsich,
The answer to the 20 wacky students is 200 fingers because I added 20 tens together and got 200. For my equation I did 20×10=200.
Your student,
Shea
January 18th, 2012 at 3:56 pm
Dear Mr.Salsich and class,
I love the blog!
I also figured out the answer to the wacky students problem. So if ten students was 100 fingers then 20 students would be 200 fingers.
Your friend,
Kayla
January 18th, 2012 at 3:58 pm
Dear Mr. Salsich,
The answer is 200 fingers. I knew this because 10 tens is 100, and if I double that, it is 200. 20 x 10 = 200.
Sincerely,
Maura
January 18th, 2012 at 3:59 pm
Dear Mr.Salsich,
I know the answer to the math problem. The answer is 200 because you skip count by 10 twenty times, like this: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 you will get to 200
your friend,
Chris
January 18th, 2012 at 4:01 pm
Dear Mr. Salsich,
I figured out how to solve it. You do 10 x 10 = 100 then double that. So 20 x 10 = 200
That is how I solved it.
your student
Creighton
January 18th, 2012 at 4:02 pm
Dear Mr. Salsich,
I think all our pictures are awesome!
I also have the answer for the wacky students question. Here it goes: I know 10 tens = 100. So, 20 tens must equal 200. Am I right? Or am I wrong?
Your student,
Taylor
January 18th, 2012 at 4:03 pm
Dear Mrs. Mckenzie,
I solved the problem by counting by fives 5,10,15,20,25,30,35! It was really easy. So, 35 dinosaurs can stay dry.
your blogging buddy,
Sophia
January 18th, 2012 at 4:07 pm
Dear Mr. Salsich and class,
This is how I figured it out;
10 x 10 =100
10 x 20 =200
I know its 200 because I know that 10 x 10 =100 so 10 x 20 = 200 (and 10 x 30 =300).
Your friend,
Hanna
January 18th, 2012 at 4:11 pm
Dear Mrs.Mckenzie,
I liked your comment. I solved your times question with repeated addition. The answer is 35. The repeated addition is 5+5+5+5+5+5+5 = 35.
your friend,
Nate
January 18th, 2012 at 4:12 pm
Dear Mr. Salsich,
I figured out the answer to the wacky students question. Since 10 groups of 10 is 100, 20 groups of 10 would be 200.
from,
Bryan
January 18th, 2012 at 4:14 pm
Dear Mr. Salsich,
I think I have the answer to the 20 wacky students problem. I think the answer is 200 because I know 10 x 10 = 100, and 100 x 2 = 200. So, there are 200 fingers in all.
Your friend,
Braedon
January 18th, 2012 at 8:17 pm
Some animal questions (threw in a few tricky ones, but I’m sure you all can handle them).
There were six ants crawling on my arm. How many legs did I feel?
My dog is six years old. How old is he in dog years?
Seven pigs have triplets. How many piglets did they have in total?
Maggie took a trip to the Mystic Aquarium and saw 12 sea jellies. How many brains did all those sea jellies have?
She also saw eight squid. How many tentacles is that?
And here is one bonus question…
Bob got hungry and headed down to the local doughnut shop. He ordered three baker’s dozen doughnuts. How many doughnuts did he get? And, yes, he ate every last one!
Best,
Bob
January 20th, 2012 at 2:41 pm
Dear Bob,
I like your comment!
The problem I’m going to solve is the one about the sea jellies and how many brains they have. Here is the answer, jellies have NO brains! The multiplication problem for this would be 12×0=0.
Love,
Shea in Mr. Salsich’s class
January 20th, 2012 at 2:48 pm
Dear Bob,
I hope you saved some doughnuts for me! I solved the problem by repeated addition sentence I know that 13+13+13=39 so you have your answer!
your very hungry friend,
Sophia
p.s please get me a jelly filled one!
January 22nd, 2012 at 10:45 pm
Sophia:
The number of doughnuts I’m saving for you = the number of brains a sea jelly has.
Ha ha.
Take care,
Bob
January 27th, 2012 at 1:02 pm
Dear Daddy,
You have to save some donuts for me! And if you say 1, just multiply that 39 times and give that number to me.
Love,
Maura
January 20th, 2012 at 2:50 pm
Dear Bob,
I solved your times problem like this: I added 13+13+13. First I add 3 tens (30) and the three 3′s (9) and it = 39. So you ate 39 donuts.
from,
Nate
January 20th, 2012 at 2:52 pm
Dear Bob,
You felt 36 legs on you because if you skip count like this 6,12,18, 24, 30, 36 then you will get to 36. So you felt 36 legs on you.
Your friend,
Chris
January 20th, 2012 at 2:52 pm
Dear Bob,
I solved question 2. Your dog would be 42. I got that from skip counting in my head like this 6,12,18,24,30,36,42 so that is how I got the answer.
Your friend,
Luke
January 20th, 2012 at 2:53 pm
Dear Daddy,
I know that you were not fair and ate 39 donuts without me! I was a really good detective and knew that the answer is 39 by adding 10+10+10, and then 3+3+3. Then I added that together. I found out that 3 x 13 = 39.
Love,
Maura
January 20th, 2012 at 2:54 pm
Dear Bob,
I’m solving the one about the dog.
My multiplication sentence would be 6×7. I take six 7′s and turn it into 3 groups of 14. I would count the three 14′s and add them up to et 42.
From,
Joseph
January 20th, 2012 at 2:57 pm
Dear Bob,
I solved it like this;
6×7=42
6+6+6+6+6+6+6 = 42
From,
Hanna
January 20th, 2012 at 2:59 pm
Dear Bob,
Great comment! The answer to the ant question was 36 because 6 times 6 equals 36. The answer to the dog question was 42 because 6 times 7 equals 42. The answer to the squid question was 64 because 8 times 8 equals 64 The answer to the sea jellies question is 0 because sea jellies have no brain! So, 12 x 0 = 0.
From,
Joey
January 20th, 2012 at 3:00 pm
Dear Bob,
You gave us lots of sensational, super-confusing math problems!
I have the jellyfish problem: They have no brains! 12×0=0! (Nice trick!)
I also have the doughnut answer. A baker’s dozen is 13 doughnuts. 13+13+13=39, because 10+10+10=30, and 3+3+3= 9. 3×13=39. So you ate 39 doughnuts total! Wow! You must’ve been starved!
Sincerely,
Taylor
January 20th, 2012 at 3:01 pm
Dear Bob,
If there were 6 ants crawling up your arm there would be 36 legs. I write the number sentence 6×6 then I skip count by 6′s and write the answer 6×6=36.
From
Dylan
January 20th, 2012 at 3:05 pm
Dear Bob,
I’m very happy to see that you’re posting comments like LIGHTNING BOLTS. I figured out your doughnut question. Here is how: I added each 10 to make 30 then I did the threes and that would be 39, so 39 is the answer. I added the threes by going 3,6,9.
Now I am going to tell you the answers to all of the questions in order :
#1 36
#2 49
#3 24
#4 0
#5 48
#6 39
from ,
Carly
P.S next time do harder ones. Please do 9′s because I know a trick
January 18th, 2012 at 9:53 pm
Dear Mr. Salsich & Wacky Students,
I love the fact that you used such lovely drawings to solve your multiplication problems. I will have to use this trick some time soon. It makes for great compositions! You are very lucky to have both creative and mathematical talents.
When I plan out my paintings, I am always using math to figure out measurements and final sizes. So here is a problem that I need help with: If I have 6 paintings where the length of each is 10 inches long, how long are they if they are hung side by side? I could really use your help on this because the wall that I have is only 40 inches long. Will my paintings fit on this wall?
Thanks,
Miss Millie (Taylor’s Mom)
January 20th, 2012 at 6:11 pm
Dear Mrs.Donovan,
I love your question.
Also if you put the paintings side by side on the wall then you would need a bigger wall because if your wall is 40 inches long and the pictures side by side are 60 inches long then you would need to take one or two pictures down. Because 6×10=60 so 60 is your answer. Because 10 six times is 60.
Your friend,
Kayla
January 20th, 2012 at 3:07 pm
Dear Bob,
You ate 39 doughnuts. I did 12+12+12 to get 36. Then I counted the ones to get 39.
From,
Jennifer
P.S. I like chocolate doughnuts.
January 22nd, 2012 at 11:05 pm
Magnificent Multiplication Mathematicians:
Apparently there is no fooling any of you. Nice job answering all the questions correctly AND using a variety of methods. Now that we have some snow, I think it is time for me to eat my 39 doughnuts and hibernate. Good night.
But first, a bonus (football) question:
There is only one way to score 4 points in an American football game. Using multiplication, explain.
Super bonus:
There are three ways to get to 6 points. Use a multiplication sentence to show each way.
Best,
Bob
January 24th, 2012 at 11:06 pm
Dear Mr. Salsich,
I figured out the multiplication problem and the answer is 200. I figured this out by using a little trick that I know: you do 2 x 1 = 2 and just add the two zeros at the end of that number, and you get 200.
I also really liked the multiplication problems that your class drew. The ones I liked the best are the one about jelly blobs and sea serpents.
One everyday multiplication problem is chairs and desks. If a teacher would want to arrange the desks a different way, then he would use a multiplication problem to figure out the best way. If there were 20 students, then he might arange the desks in 5 rows of 4. Another one is a tile floor. A carpenter might need to make a floor of 100 tiles but the room is rectangular. If it was a skinny room, the carpenter could use a 20 by 5 array.
From your former student,
Alison
January 25th, 2012 at 7:44 am
Hi,
I loved your multiplication problems and the wonderful artwork!
Here are a few problems to solve:
1. Two sets of twins are celebrating a birthday. Each hungry twin eats two delicious cupcakes. How many cupcakes did the twins devour?
2. Two hungry cats scamper into the garage. Two frightened field mice run to hide. The chase is on! How many paws are racing around the garage?
Happy solving,
Alice
January 27th, 2012 at 12:46 pm
Dear Joey’s mom,
I love your question.
Also if there was 4 kids and they ate 2 cupcakes then all you would have to do is count by twos 4 times. 2,4,6,8. The two sets of twins devoured 8 cupcakes.
Your friend,
Kayla in Mr.Salsichs class
January 27th, 2012 at 12:47 pm
Dear Joey’s Mom,
Two sets of twins would be four children. If each child eats two cupcakes, all I have to do is add 2 four times. 2, 4, 6, 8. The answer is 8.
Sincerely,
Maura
January 27th, 2012 at 12:48 pm
Dear Joey’s Mom,
There would be 16 paws. I figured this out because the cats = 8 paws and the mice = 8 paws. Then, 8 + 8 = 16
From,
Carly
January 27th, 2012 at 12:49 pm
Dear Alice,
Two sets of twins ate 8 cupcakes altogether. I got this because I skip counted by 2′s- 2,4,6,8 than you would get to 8.
Your friend,
;lol: Chris
January 27th, 2012 at 12:55 pm
Dear Joey’s mom
How did you come up with 2 cats? Do you have two crazy cats messing up your garage?
Joey’s friend
Creighton
January 27th, 2012 at 12:50 pm
Dear Mom,
Those are some great questions! Lets see, the answer to the twins question is 4 twins because 2+2=4. And the answer to the cat question was 16 because 4+4+4+4=16
Your son,
Joey
January 27th, 2012 at 12:57 pm
Dear Joey’s mom,
the answer to your question is 16. I know that because cats have 4 paws so 2 cats have 8 paws, and 8 + 8 equals 16
Your friend,
Joe the human calculator