In this activity, students practice identifying line segments, intersecting lines, and parallel lines. Students find these figures first on a map and then in the alphabet. In both contexts, they encounter marks that may appear to be segments but are not actually perfectly straight, or pairs of lines that appear to be parallel but are not exactly so. Students have an opportunity to attend to precision when analyzing the given images (MP6).

When analyzing some letters in the alphabet, students may say that J and O have lines or segments that turn. Remind students that we have defined a line as being straight, so a line segment is also straight. In the letter J, the segment can be distinguished from the curve.

• Select students to share their responses to the first question. Display their work (using a document camera or projector), or display the map and ask students to show their lines on it.
• To elicit the use of precise vocabulary and encourage more participation, consider asking:
  • “¿Hubo pares de rectas que al principio pensaron que eran paralelas, pero después se dieron cuenta de que no lo eran? ¿Cómo lo descubrieron?” // “Were there any pairs of lines that you assumed at first to be parallel but then realized that they are not? How did you find out?”
  • “¿Alguien más puede mostrar otro par de rectas paralelas? ¿Y otro par de rectas que no sean paralelas?” // “Can someone else show a different pair of parallel lines? A different pair of lines that are not parallel?”
• “¿Dos segmentos tienen que tener la misma longitud para ser paralelos? Por ejemplo, el segmento horizontal de arriba de la ‘E’ y el segmento horizontal del medio tienen longitudes distintas. ¿Son paralelos?” // “Do two segments have to be the same length to be parallel? For example, the top horizontal segment in E and the middle horizontal segment have different lengths. Are they parallel?” (Yes. The segments are parts of lines that are parallel. The lengths of the segments do not determine if they are parallel.)
• “¿Cómo podemos completar estas afirmaciones?” // “How might we finish these statements?”
  • “Todas las rectas que se intersecan _____” // “All intersecting lines _____.” (cross each other)
  • “Algunas rectas que se intersecan _____” // “Some intersecting lines _____.” (form square corners, make an “X” shape)
  • “Todas las rectas paralelas _____” // “All parallel lines _____.” (never cross)

In this activity, students look for parallel and intersecting lines in their environment and record them in a drawing. Students notice that parallel and intersecting segments can be found in logos and symbols, and use these figures to design their own logo. When students recognize mathematical features of objects in their classroom and design a logo with intersecting and parallel line segments, they model with mathematics (MP4).

If time permits, ask students to display their drawings and logos, and complete a Gallery Walk.

• “¿En qué parte de nuestro salón encontraron rectas paralelas?” // “Where did you find parallel lines in our classroom?” (windows, doors, floor tiles, cubbies, desks)
• “¿En qué parte encontraron rectas que formaban esquinas cuadradas?” // “Where did you find lines that make square corners?” (windows, doors, floor tiles, cubbies, desks)
• “¿En qué parte encontraron rectas o segmentos que no formaban esquinas cuadradas cuando se intersecaban?” //  “Where did you find lines or segments that do not make square corners when they intersect?” (design on the doors, slant on the ceiling or floor, railings of stairs, braces or brackets of desks or chairs, hands on the clock)
• If time is limited, ask partners to trade their logo designs, look for the required lines in each other’s work, and share feedback.
• If more time is available, ask students to display their designs and visit others’ work in a Gallery Walk. In each design, students should look for parallel and intersecting lines and line segments.