View full screen in your browser. This ITP allows you to create a number of connected vertices on a grid. The grid size can be changed, and the grids hidden and revealed. As each vertex is created it is labelled and joined to the previous one. To close a shape select a vertex at any point and drag it onto the required point to create a closed shape. Once a shape has been created, its vertices can be dragged to new positions to create new shapes. Lengths of sides can be measured using a ruler.
The angles created at vertices can be measured using the protractor and their values can be displayed or hidden. For reflex interior angles the value of the exterior angle is shown. You can use the ITP to demonstrate and explore properties of shapes, such as the internal angles of different pentagons and the properties of opposite sides of various parallelograms in different orientations.
View full screen in your browser. This ITP allows you to place shapes around a point and investigate their angles. You can opt to display the shapes in one, two or four quadrants. The first shape is placed on the screen in the first quadrant with one of its sides horizontal. Additional shapes are rotated around the central point to fit against the previous shape. In some shapes side lengths and angles are generated randomly. Shapes generated can be dragged to new positions and overlaid to form new intersecting shapes and angles.
View full screen in your browser. This ITP displays regular polygons with 3 to 10 sides. A background grid can be revealed and hidden and the displayed polygon can be enlarged using the pointers on the polygon button. The polygon can be translated and rotated. A vertex on the polygon can be dragged to another position to change its shape and properties. Double clicking on a vertex allows you to add remove the vertex or to add an extra vertex at the mid point of an adjacent side. You can use the ruler or protractor to measure dragging it and using the circular button to rotate it to the required position. The ITP can be used to explore the properties of regular and irregular polygons. Children’s understanding of the angular properties of polygons can be developed. Children’s hypotheses about properties of sides and internal and external angles can be verified by measurement. Using the grid, children can explore the areas of polygons; identify which polygon’s vertices fit onto the grid points and look at how they calculate the areas of rectilinear shapes.