Problem
Subtracting the smaller from the larger in each group gives differences 1, 0, 2, 3.
The larger count splits into a part that matches the smaller one-for-one and a leftover part. That leftover is exactly the difference, and subtracting is what isolates it.
2.MD.D.10Systematic ListFor each group, subtracting the smaller count from the larger count gives the difference between the number of girls and boys.
The larger count is really the part that matches the smaller count one for one, plus the extra that has no match, and that extra is the difference.
You can pair each student in the smaller count with one student in the larger count, so the matched parts are the same size.
The larger count splits with no overlap into the matched part and the leftover part, so those two parts add back to the whole larger count.
Taking the smaller count away from the larger count undoes adding it on, so what is left is exactly that extra.
Comparing 1, 0, 2, and 3, the greatest difference is Group 4's 3.
Reading a graph means comparing its columns. Lining up all four differences in a row makes the single greatest value easy to spot.
3.MD.B.3Tables And GraphsGroup 4 has 2 girls plus 5 boys, for a total of 7 students.
A group's total is just its two parts — girls and boys — put back together. Adding those two counts gives the whole.
2.MD.D.10Tables And GraphsFind each group's difference, compare them, then add the two counts of the group that wins.