Posted by Lisa on Tuesday, October 2, 2012 at 5:57pm.
Boys and girls=25
but boys is girls+9
so girls+9+girls=25
twice girls+9=25
twice girls=16
girls=8
boys=nine plus eight
Ahhh, this would be so easy with algebra as was shown by Ms Sue and Shelley, but I guess we can't use algebra for a grade 3
How about making two columns where the two numbers add up to 25 until we see a difference of 9
e.g.
10 15 ----> difference is 5
9 16 ----> difference is 7
8 17 ----> difference is 9 , YEaaahh!
5x5=25
I don't understand?
Suppose the teacher says to the class:
"We're going to play a game and to play it we must have exactly the same number of boys as we have girls. So 9 of you boys will have to go to another room while we play this game."
So 9 boys get up and leave the room. That leaves 25-9 or 16 students in the room, 8 girls and 8 boys. Then after the game is over the 9 boys return. Now there are 8 girls and 8+9 or 17 boys.
Edwin
20 tiles in 5 rows
solve a simpler problem
You can tell her to subtract. Enjoy
get out 25 blocks then pull 9
title is class collection data week 1
Use structure what property of addition is showmen in the following number sentence ?explain.7+(3+5)=(7+3)+5
Use Trial and error
5+14=19. No
Its too hard
Start with the idea that some of the students can be paired (boy/girl, boy/girl, boy/girl...
Then ask what (or who) will be left over after the pairing.... 9 boys. So have the child set the 9 boys apart... so instead of pairing 25 students we'll pair....be sure to ask the question rather than just tell... Most 8yr-olds will be able to figure out the equation required is 25-9=16. Help only as needed.
Now we have 16 students that we are going to pair boy/girl, boy/girl... How many pairs. So, with only what prompting is needed, that's how many girls? How many boys? May need a reminder about the 9 set aside before.
Students adds the 8 paired boys with the 9 stag boys = 17. 8 girls. Double check that the boys + girls adds up to the 25...
Yeah! Math isn't so terrible after all.
:D
25-9=16 boys. the rest are girls
there are 16 girls
students=25
boys=25-9=16
boys & girls=16
girls=16 divided 2=8
boys=8+9=17
girls=8
make sure your answer is correct:17+8=25
15
how many apples can you dived by 60
in 10 mients
30
Just explain how to use X for him.
16