Lesson 3: Graph Ratio Tables6.AT.3a

I can…

I can graph the values from a ratio table as points on the coordinate plane.

Key words

• Coordinate plane — A grid with a line going across and a line going up to plot points.
• Ordered pair — Two numbers (x, y) that tell where a point is on a grid.
• Linear pattern — Points that make a straight line on a grid.
• Proportional — Two amounts that grow together at the same rate.
• Origin — The point (0, 0) where the two grid lines cross.

Steps

1. The recipe uses 2 ounces of sauce for every 1 sundae.
2. I put sundaes on the x-axis and ounces of sauce on the y-axis.
3. For 1 sundae I need 2 ounces, so I plot the ordered pair (1, 2): right 1, up 2.
4. For 2 sundaes I need 4 ounces, so I plot (2, 4): right 2, up 4.
5. When I connect (1, 2), (2, 4), (3, 6), they form a straight line through the origin (0, 0).

Try it

A ratio table shows cups of rice to cups of water: (1, 2), (2, 4), (3, 6). If you plot these points, the line passes through which point?

Check your answer

(5, 10)

The ratio is 1:2, so for 5 cups of rice you need 5 × 2 = 10 cups of water. The point (5, 10) continues the pattern.

Sentence starter

I know ___ because ___.

Goal: I can explain my graph using the words coordinate plane, ordered pair, origin, and proportional.