Inside Mathematics
Rhombuses
Just what does it take to show two rhombuses are similar? The assessment task asks pupils to develop an argument to show that given quadrilaterals are rhombuses. Class members also use their knowledge of similar triangles to show two...
Illustrative Mathematics
A Midpoint Miracle
Young geometers develop one of the fundamental properties of quadrilaterals (connecting side midpoints gives a parallelogram) in this short but thought-provoking exercise. Using a combination of hands-on techniques and abstract algebraic...
Key Curriculum Press
Properties of Special Parallelograms
Rhombuses, rectangles and squares are have special properties. In this lesson, young geometers investigate and make conjectures about diagonals, angles, and parallel lines of parallelograms.
Curated OER
Property Lists for Quadrilaterals
High schoolers establish classifications of shapes by various properties (angles, sides, etc.). They introduce the important properties of common shapes. Students develop an awareness of the wide variety of ways the 2-D shapes can be alike.
Bytes Arithmetic
Geometry Pad+
Graphing paper, pencil, ruler, protractor, and compass, all get replaced or supplemented with this dynamic geometry application. Here, you can create, move, and scale many different shapes, as well as, explore and change their properties...
Curated OER
Geometry: Classifying Quadrilaterals
Students use construction technology to identify and find relationships between the attributes of various quadrilaterals. They make and test conjectures about the distinguishing properties of parallelograms, rectangles, rhombuses,...
Texas Education Agency
Texas Gateway: Making Conjectures About Quadrilaterals
Given examples of quadrilaterals and their component parts, the student will use explorations and concrete models to prove a quadrilateral is a parallelogram, rectangle, square, or rhombus using opposite sides, opposite angles, or...