Grade 3 updates continue this summer, this time with Module 7 Topic E, where students continue to grow their understanding of polygons, focusing on triangles and rectangles. Along the way, they practice skills like finding perimeter, identifying the lengths of missing sides, and finding area. They explore all of these concepts while working with our virtual student, Tom, who’s on a quest to build as many things as he can over the summer!

In the first task, students begin by working with triangles and identifying the number of sides that are equal in length. Their next challenge is to select the triangle that matches a description, which requires students to think critically about the number of sides that are equal and how that affects how the polygon looks.

Tom moves into the next phase of his project–creating wire models. As he makes triangles and quadrilaterals, students label the lengths of the sides and find the total amount of wire needed to create the polygon–a clever way to practice the skill of finding the perimeter.

When Tom’s friend comes to visit, she accidentally breaks a step on the tree house ladder, which our clever builder feels confident in fixing! Students help by finding the missing lengths of the sides of a rectangle, which they do by recalling the property of rectangles having equal opposite sides. They continue building this skill without the help of visual models as our virtual friend builds his pet a doghouse.

Next, Tom has an idea of making his dog a cozy blanket for his new home, which requires him to cut a perfect rectangle (identifying the lengths of the missing sides) and measure the length of the trim he needs (finding the perimeter). Our students learn to compose expressions to find the perimeter of a rectangle, then narrow down 3 additions into 2 identical expressions.

The students solidify their understanding of finding the perimeter of rectangles by solving word problems about constructing a new flower bed, hanging party flags around a room, and directing a delivery robot around a park! 

 

When Tom invites his friend up to his treehouse, she has a few suggestions for improvements to his model rocket display–adding stars and a sun. The friends begin by bending bits of wire to create new shapes. As they help the pair, students come to find out that the same length of wire can be bent in different ways to create different triangles that all have the same perimeter. Then, knowing the perimeter and the lengths of two sides, students practice finding the length of the third side of a triangle. 

With their space model complete, our friends embark on a new mission to help their cousin build his fence. Students apply what they know about perimeter and rectangles to find the lengths of three missing sides. First, they label the sides, keeping in mind that opposing sides of a rectangle are equal in length. Next, they compose an equation with the missing values, then divide and subtract to solve for the missing sides.

Tom and his friend then move on to their final creation: assembling their new railway kit. First, though, they have to determine if it will even fit in their treehouse! To find out, students must find the area of a rectangle by multiplying its length and width. They apply this same skill to finding the area of rectangular train cars to see if they have enough paint to cover them. Along the way, they come to find out that although two rectangles may have the same area, their perimeters can differ.

In the next and final task, they find the converse to be true too: two rectangles can have different areas but the same perimeter. We leave Tom and his friend with a completed railway set and a great sense of achievement about all the important math work they’ve done.

For Students: This new topic provides students with repeated opportunities to explore practical applications of perimeter of triangles and rectangles. By solving problems supported by visual models to word problems, students apply their understanding of these polygons and their properties in engaging and authentic ways. They also begin to relate what they understand about side lengths and perimeter of rectangles to their area, and again apply this to real-world scenarios.  

For Teachers: This topic helps students begin to see real-world applications of their budding skills in finding perimeter and area. Students also begin exploring simple algebraic equations as they solve unknown side problems, which forms an important foundation for working with these problems in increasingly complex ways in later grades. 

You can explore these new tasks in Grade 3 Module 7 Topic E in your teacher dashboard now. We hope your students have fun on their building adventures and pick up some new skills along the way!

Please reach out at support@happynumbers.com if you have any additional questions or need for support. We’re happy to help!