# Common Core Standards: Math See All Teacher Resources

#### The Standards

# High School: Number and Quantity

### Vector and Matrix Quantities HSN-VM.C.6

**6. Use matrices to represent and manipulate data, e.g., to represent payoffs or incidence relationships related in a network.**

Students should understand what a matrix is and how to use it. No, not *The Matrix*.

The textbook definition of a **matrix** is, "A rectangular array of numbers." Yeah, that helps a lot. A more workable definition might be, "An organizational system that sorts numbers into rows and columns."

Students can think of matrices as organizing information into a chart—one column for rate, another for time, and another for distance, for example. That's kind of what we're talking about here.

In a matrix, rows are the horizontal groups of numbers, reading from left to right. Columns are the vertical groups of numbers, reading from top to bottom. Just like the rows and columns in excel spreadsheets and Bingo boards.

Let's say you're preparing your students for college applications. (Good luck.) They can sort out their "safe" schools, "reach" schools, and a number of schools that fall somewhere in between. As they wait for those wonderfully fat envelopes full of good news, you can subtly hint to them that they should figure out finances. Using matrices.

First, they can make a row for each school. Then make columns for tuition, room and board costs, definite scholarships, work-study, and miscellaneous—any other sources of income that might not fit anywhere else.

Their end result might look something like this, but filled with numbers other than 0.

Schools | Tuition | Room and Board | Scholarships | Work-Study | Miscellaneous |

Standford | 0 | 0 | 0 | 0 | 0 |

Princetown | 0 | 0 | 0 | 0 | 0 |

Harward | 0 | 0 | 0 | 0 | 0 |

Yayle | 0 | 0 | 0 | 0 | 0 |

There, at a glance, they'll have their financial picture for college. No wading through pages and pages of tactful letters; instead, a simple matrix listing what each school will cost them.

Essentially, students should understand that matrices are friends, not enemies.