Mathalicious: It's a Date
Mathalicious

In this lesson, students examine some other ways to keep track of dates, and use number sense and function concepts to convert among different calendars.

Khan Academy: Algebra 1
Khan Academy

The Algebra 1 course, often taught in the 9th grade, covers Linear equations, inequalities, functions, and graphs, Systems of equations and inequalities, and more.

Real World Math: Exploratory Lessons - Crop Circles 2
Real World Math

This lesson takes an inquiry-based approach to central-pivot irrigation systems with the use of spreadsheets. 

Real World Math: Space Lessons - Lunar Sports
Real World Math

One of the concepts discussed in the Lunar Field Trip activity is that the gravitational forces on the Moon are one-sixth that on Earth.

Illuminations: Building Connections
Illuminations (National Council of Teachers of Mathematics)

This lesson focuses on having students make connections among different classes of polynomial functions by exploring the graphs of the functions.

Illuminations: Modeling Orbital Debris Problems
Illuminations (National Council of Teachers of Mathematics)

In this lesson, students examine the problem of space pollution caused by human-made debris in orbit to develop an understanding of functions and modeling.

Illuminations: Domain Representations
Illuminations (National Council of Teachers of Mathematics)

Students use graphs, tables, number lines, verbal descriptions, and symbols to represent the domain of various functions.

NRICH: Translating Lines
NRICH (University of Cambridge)

Investigate what happens to the equation of different lines when you translate them. Try to predict what will happen. Explain your findings.

NRICH: Reflecting Lines
NRICH (University of Cambridge)

Investigate what happens to the equations of different lines when you reflect them in one of the axes. Try to predict what will happen. Explain your findings.

NRICH: Diamond Collector
NRICH (University of Cambridge)

Collect as many diamonds as you can by drawing three straight lines.

NRICH: Perpendicular Lines
NRICH (University of Cambridge)

Position the lines so that they are perpendicular to each other. What can you say about the equations of perpendicular lines?

NRICH: Parallel Lines
NRICH (University of Cambridge)

How does the position of the line affect the equation of the line? What can you say about the equations of parallel lines?