X-post general board singapore bar graph help--PLEASE!!

[Caitilin]

singapore bar graph help--4A Please!! 300 children are divided into 2 groups. One group has 50 more children than the second group. How many are in each group.

 

I know how to solve this problem algebraically, but I don't know how to do it with the Singapore bar graphs. Can anyone help me explain this to ds?

[RootAnn]

Okay, this is coming from a non-Singapore-user, so this might not be the best answer.

 

Draw two bars - one slightly longer than the other. Pick the longer bar & put a line on it equal to the length of the shorter bar.

 

-----------

 

----------|----|

 

Kinda-like the above. Now, label the short section on the end of the longer bar "50." The kid knows the two bars together make 300, which means the two sections of bars (the shorter bar and the short section of the longer bar) together are 300-50 and are also equal to each other (because they visually see this with the bar graph).

 

Thus, they know (300-50)/2 = the length of the shorter bar.

The shorter bar + 50 = the bigger group.

 

Does that make sense?

[Melissa B]

Okay, this is coming from a non-Singapore-user, so this might not be the best answer.

 

Draw two bars - one slightly longer than the other. Pick the longer bar & put a line on it equal to the length of the shorter bar.

 

-----------

 

----------|----|

 

Kinda-like the above. Now, label the short section on the end of the longer bar "50." The kid knows the two bars together make 300, which means the two sections of bars (the shorter bar and the short section of the longer bar) together are 300-50 and are also equal to each other (because they visually see this with the bar graph).

 

Thus, they know (300-50)/2 = the length of the shorter bar.

The shorter bar + 50 = the bigger group.

 

Does that make sense?

 

 

This is the way the Singapore book teaches it too. :)