Counting
OOO
3
No straight sides, one curved line.
circle
2 + 1=
3
2-1=
1
OOOOO
5
Has only 3 sides.
triangle
3+1=
4
4-1=
3
OOOOO O
6
4 sides of the same length.
square
5+1=
6
6-1=
5
OOOOO OOO
8
Has 8 sides
octagon
6+1=
7
8-1=
7
OOOOO OOOOO
10
Has 2 long sides and 2 short sides.
rectangle
9+1=
10
10-1=
9