CK-12 Foundation
Sums of Finite Arithmetic Series: Triangular Numbers
Using a slider, scholars build triangular numbers and their associated rectangles and use the geometric display to find the pattern to determine the next triangular number. They then relate that number to the area of the rectangle to...
CK-12 Foundation
Sequence of Partial Sums: Partial Sums
Have some fun building squares out of triangles. Pupils investigate the partial sums of odd numbers. Using the sum of the first four odd numbers, learners see that it can be rewritten as a sum containing a triangular number. Simplifying...
Virginia Department of Education
Quadratic Modeling
Use a one-stop resource for everything you'd possibly want to teach about quadratic functions and models. Scholars analyze key features of quadratic functions as well as transformations of functions through seven activities....
Bowland
Pointzero: Confined
Groups plan their escape carefully. Three three-tiered puzzles help a story character escape their situation, each involving integer sequences, transformations, and geometric constructions. The teacher resource includes slides and...
Curated OER
Investigating Square and Triangle Numbers
Fifth graders build increasingly larger squares and triangles using pattern blocks. They record the growth patterns on a chart and look for corresponding numerical patterns. Students describe the patterns they find and use them to...
Curated OER
Number Patterns: Triangular Numbers
Students explore number patterns. In this number pattern lesson, students discover the attributes of triangular numbers as well as the number patterns associated with them as they practice sequencing 10 triangular numbers.
Curated OER
Triangular Numbers
In this triangular numbers instructional activity, students create a table of triangular numbers, write a formula for the nth number, and determine the sum of any two consecutive triangular numbers. This two-page instructional activity...
Curated OER
Triangular Numbers Are Everywhere !
In this math worksheet, students observe that the triangular numbers are associated with the sums of consecutive natural numbers beginning with 1.
Curated OER
Easy Worksheet: Special Numbers
In this special numbers worksheet, students solve 4 short answer problems. Students find various terms in the Fibonacci sequence, triangular number sequence, and the natural numbers in Pascal's Triangle.
Curated OER
Number Patterns: Triangular & Square Numbers
Students explore the patterns found in triangular and square numbers. In this number pattern lesson, students complete a worksheet exploring the relationship between triangular numbers and square numbers.
Curated OER
The Truth About Triangles and Squares
Fourth graders investigate the patterns associated with both triangular and square numbers. They use counters as manipulatives to depict the numbers as needed but focus on problem solving using mental math techniques.
Cut the Knot
Cut the Knot!: What Is a Number?
Casual and clear but definitely upper-level discussion of rational, real, imaginary, and several other types of numbers. Links to related sites.
National Council of Teachers of Mathematics
The Math Forum: Pascal's Triangle
You will find the triangular numbers in Pascal's triangle.
Illustrative Mathematics
Illustrative Mathematics: F Le Triangular Numbers
The goal of this task is to work on producing a quadratic equation from the arithmetic context of triangular numbers. Aligns with HSF-LE.A.
Wolfram Research
Wolfram Science World: Pythagoras of Samos (Ca. 560 Ca. 480 Bc)
This site from ScienceWorld provides a short, informative description of many of the contributions of Pythagoras to mathematics. Links exist to some of the contributions as well as to additional information.
Other
Fascinating Triangular Numbers
Patterns of numbers don't come along every day, and so when they do, they need to be bragged about! The basic definition of triangular numbers begins this site which also lists many of the properties of these numbers, highlights the...
Math Is Fun
Math Is Fun: Common Number Patterns
Developed by a mathematics teacher from the UK, this page identifies and illustrates several common number patterns.
Curated OER
Displaying Triangular Numbers
Patterns of numbers don't come along every day, and so when they do, they need to be bragged about! The basic definition of triangular numbers begins this site which also lists many of the properties of these numbers, highlights the...