This short video and interactive assessment activity is designed to teach third graders about grouping with illustrations - word problems.

This short video and interactive assessment activity is designed to teach second graders about understanding grouping with illustrations.

This short video and interactive assessment activity is designed to teach fourth graders about finding the total number: given remainder and number needed.

This task adds some rigor to the activity of growing bean plants. By collecting growth data, students practice measuring and recording length measurements.

This task is designed to make students think about the meaning of the quantities presented in the context and choose which ones are appropriate for the two different constraints presented. In particular, note that the purpose of the task is to have students generate the constraint equations for each part (though the problem statements avoid using this particular terminology), and not to have students solve said equations.

This problem asks the students to represent a sequence of operations using an expression and then to write and solve simple equations. The problem is posed as a game and allows the students to visualize mathematical operations. It would make sense to actually play a similar game in pairs first and then ask the students to record the operations to figure out each other's numbers.

This short video and interactive assessment activity is designed to teach second graders an overview of subtraction (numbers to 100) - word problems.

This marbel counting iteration of greater than, less than, and equal to with a specific "target number" help strengthen the concept for students.

An interactive applet and associated web page that shows how right triangles that have the hypotenuse and one other leg the same length must be congruent. The applet shows two right triangles, one of which can be reshaped by dragging any vertex. The other changes to remain congruent to it, and the hypotenuse and leg are outlined in bold to show they are the same measure and are the elements being used to prove congruence. The web page describes all this and has links to other related pages. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

This problem could be used as an introductory lesson to introduce group comparisons and to engage students in a question they may find amusing and interesting. More generally, the idea of the lesson could be used as a template for a project where students develop a questionnaire, sample students at their school and report on their findings.

This task involves fraction multiplication that can be solved with pictures or number lines.

In this activity students measure their hand span. A line graph is used to record the data from the glass.

In this group task students collect data and investigate whether there is a relationship between height and hand size among the students in the class.

Students explore the concept of similar right triangles and how they apply to trigonometric ratios. Use this lesson as a refresher of what trig ratios are and how they work. In addition to trigonometry, students explore a clinometer app on an Android® or iOS® device and how it can be used to test the mathematics underpinning trigonometry. This prepares student for the associated activity, during which groups each put a clinometer through its paces to better understand trigonometry.

This is a challenging task, suitable for extended work, and reaching into a deep understanding of units. The task requires students to exhibit MP1, Make sense of problems and persevere in solving them. An algebraic solution is possible but complicated; a numerical solution is both simpler and more sophisticated, requiring skilled use of units and quantitative reasoning. Thus the task aligns with either A-CED.1 or N-Q.1, depending on the approach.

This is an activity about utilizing proportional mathematics to determine the height of lunar features. Learners will use the length of shadows to calculate the height of some of the lunar features. This activity is Astronomy Activity 6 in a larger resource entitled Space Update.

A web page and interactive applet illustrating the properties of a heptagon (7 sided polygon). The applet shows a heptagon where the user can drag any vertex to reshape it. User can see that the interior and exterior angles are constant in a regular heptagon, but vary in an irregular version. Controls allow the display or hiding of the diagonals, and triangles within the heptagon. The web page lists the properties of a heptagon including interior angles, exterior angles, sum of exterior angles, area, number of diagonals and number of internal triangles. Links to pages with generalized properties of all polygons. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

An interactive applet and associated web page that demonstrate how Herons Formula can be used to find the area of a triangle when you know all three sides. A triangle is shown where the user can drag any vertex to reshape it. In real time while dragging, the side lengths change and the formula is recalculated on the screen. The formula can be turned off to facilitate class work. The text on the web page gives the full formula and discusses where is can be applied. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

A web page and interactive applet illustrating the properties of a hexagon (6 sided polygon). The applet shows a hexagon where the user can drag any vertex to reshape it. User can see that the interior and exterior angles are constant in a regular hexagon, but vary in an irregular version. Controls allow the display or hiding of the diagonals, and triangles within the hexagon. The web page lists the properties of a hexagon including interior angles, exterior angles, sum of exterior angles, area, number of diagonals and number of internal triangles. Links to pages with generalized properties of all polygons. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

The goal of this task is to use geometry study the structure of beehives. Beehives have a tremendous simplicity as they are constructed entirely of small, equally sized walls. In order to as useful as possible for the hive, the goal should be to create the largest possible volume using the least amount of materials. In other words, the ratio of the volume of each cell to its surface area needs to be maximized. This then reduces to maximizing the ratio of the surface area of the cell shape to its perimeter.