Calculate area contained inside the rubber band.
Geoboard:
Buttons:
0=0 Insert new rubber band
T Erase rubber band
Col Change rubber band color
A Calculate area
Drag vertices and edges.
Drag all mesh touching thumbtacks.
Zoom mesh with 'pinch zoom'.
Menu:
Square or isometric mesh.
Practice:
Calculate area contained inside the rubber band (only in square mesh).
Pick's Theorem:
A = I + B/2 -1
A = Area
I = Inner dots.
B = Border dots.
Convex, concave polygons, positive or negative areas:
Triangles
Rectangles
Squares
Tilted rectangles
Tilted squares
Tilted triangles
Farey Sunburst