The purpose of this activity is for students to plot several points with the same vertical or horizontal coordinate and observe that they lie on a horizontal or vertical line respectively (MP7). Students also plot points on the axes for the first time. Before plotting the points on a grid with grid lines, students first estimate the location of the points. This encourages them to think about the coordinates as distances (from the vertical axis for the first coordinate and from the horizontal axis for the second coordinate).

• Ask previously identified students to share their thinking.
• “¿Qué podemos decir sobre un conjunto de puntos cuando ellos tienen la misma primera coordenada?” // “What can we say about a set of points when they share the same first coordinate?” (They will be on the same vertical line.)
• Display the image from the student solution showing points with the first coordinate 5.
• “¿Cómo supieron dónde ubicar el punto que tenía coordenadas ?” // “How did you know where to put the point with coordinates ?” (I put it on the horizontal axis. I went over 5 but did not go up at all.)
• “¿Qué ocurre cuando los puntos de un conjunto tienen la misma segunda coordenada?” // “What happens when a set of points share the same second coordinate?” (They will be on the same horizontal line.)
• Display the image from the student solution showing points with the second coordinate 3.
• “¿Qué nos dice el cero que aparece en (0,3)?” // “What does the zero in (0,3) tell us?” (It means the point will be on line zero of the horizontal axis, which is the vertical axis.)
• “ es un punto importante porque es donde empezamos cuando ubicamos un punto en la cuadrícula de coordenadas. Encuentren  en la cuadrícula con la que han estado trabajando” // “ is an important point because it's where we start when we plot a point on the coordinate grid. Find on the grid you have been working with.”

In the previous activity, students noticed that points with the same vertical coordinate lie on a horizontal line and points with the same horizontal coordinate lie on a vertical line. The purpose of this activity is to reinforce this idea by asking students to plot points on a blank coordinate grid given a single point. Using this point, students can plot other points with the same horizontal or vertical coordinate. Some students may keep one coordinate the same and double or halve the other as is shown in the student solution. Other students may label points on the axes. The given point, for example, allows students to identify 4,0 and 0,2. An advantage to working with points on the axes is that these are essentially number lines with which students have been working for several years. The Activity Synthesis highlights the special nature of the points 1,0 and 0,1. All of the points where the grid lines meet can be measured off exactly after 1,0 and 0,1 are plotted. 

If students only plot one other point, consider asking:

• “El punto que está marcado es . ¿Qué sabes sobre él?” // “What do you know about the point that is plotted?”
• “¿Cómo puedes usar una de las coordenadas del punto  para ubicar y marcar un punto diferente pero que comparta esa coordenada?” // “How can you use the one of the coordinates of the point that is plotted to plot a different point with one of the same coordinates?”

• Invite students to share the points that they plotted and their reasoning.
• Plot the points as they discuss their reasoning.
• “¿Cómo ubicaron ?” // “How did you plot ?” (I know where is on the vertical axis because it has the same horizontal coordinate as . Then I halved the distance to the vertical axis and that's .)
• “Si ya saben dónde está , ¿qué otros puntos pueden ubicar en el eje vertical?” // “Once you know where is, what other points can you locate on the vertical axis?” ((2,0), (3,0), (4,0),... I can just keep marking off that distance like I do when I am on a number line.)