This lesson unit is intended to help teachers assess how well students are able to: recognize and visualize transformations of 2D shapes; and translate, reflect and rotate shapes, and combine these transformations. It also aims to encourage discussion on some common misconceptions about transformations.

This interactive activity adapted from the Wisconsin Online Resource Center challenges you to plan, measure, and calculate the correct amount of roofing material needed to reroof a house.

This problem confronts students with the idea that when collecting data to try to answer a question it is important to identify all the relevant variables, and that an over-simplistic analysis with a limited amount of information can lead to the wrong decisions.

The problem also offers the opportunity for students to practice calculating ratios, percentages and proportions.

This task provides a good opportunity to use isosceles triangles and their properties to show an interesting and important result about triangles inscribed in a circle: the fact that these triangles are always right triangles is often referred to as Thales' theorem. It does not have a lot of formal prerequisites, just the knowledge that the sum of the three angles in a triangle is 180 degrees.

The result here complements the fact, presented in the task ``Right triangles inscribed in circles I,'' that any triangle inscribed in a circle with one side being a diameter of the circle is a right triangle. A second common proof of this result rotates the triangle by 180 degrees about M and then shows that the quadrilateral, obtained by taking the union of these two triangles, is a rectangle.

This Nrich problem appears at first to be about angles and rotations, but as students explore more deeply, they may be surprised to discover links to factors, multiples and primes. The images and interactivity provide an enticing hook to stimulate students' curiosity.

This short video and interactive assessment activity is designed to teach third graders an overview of rotational symmetry.

This short video and interactive assessment activity is designed to give fourth graders an overview of rotational symmetry.

This short video and interactive assessment activity is designed to give fifth graders an overview of rotational symmetry.

Students use a variety of properties concerning circles and sectors to justify statements.

This Nrich activity provides a meaningful task for practicing rounding two-digit numbers to the nearest multiple of 10. It encourages children to record their results, notice patterns and make predictions.

In this NRich activity students will analyze a pattern on a coordinate plane in order to make predictions.

This task uses geometry to find the perimeter of the track. Students may be surprised when their calculation does not give 400 meters but rather a smaller number.

The goal of this task is to model a familiar object, an Olympic track, using geometric shapes. Calculations of perimeters of these shapes explain the staggered start of runners in a 400 meter race.

This Nrich problem lets you spot misconceptions your students have about subtraction and division of fractions, while giving students an opportunity to practice the procedures in an intriguing context - students' curiosity will be raised by the strange patterns in the calculations, and we hope they will yearn to explain what is happening.

This is the first version of a task asking students to find the areas of triangles that have the same base and height, and is the most concrete.

This is the second version of a task asking students to find the areas of triangles that have the same base and height. This presentation is more abstract as students are not using physical models.

This Nrich problem is a good opportunity to encourage children to have a system for finding all possible solutions. It is also an ideal context in which to help children deepen their understanding of factors and multiples in a playful environment.

This Nrich activity will be very useful when wishing to challenge and extend pupils' spatial awareness with 2D shapes. It can also be an exercise in perseverance.

This real world word problem requires students to figure out the scale ratio and unit rate.