Area of Triangles — Notes Packet

Sky Harbor Mission

The Triangular Skylight

You are the lead architect at Sky Harbor Studio. The city has hired your firm to design a glass skylight made of triangular panels for the new transit hub. Before the glass can be cut, you must master the area of triangles — every wrong measurement wastes expensive glass.

My Notes Level 1 Support Level 2 Standard Level 3 Enrichment

Today's objectives

Content Objective: I can find the area of a triangle using the formula A = ½ × base × height.

Language Objective: I can explain my steps using the words base, height, area, and perpendicular.

📖 See Learn It for the explanation and worked examples, and the Vocab tab for the words. These are your notes to fill in and keep.

✏️ Fill in each blank as we go. Use the Word Bank to help you.

📚 Word Bank — fill each blank with the best word

👆 Tap any word to see what it means and a picture.

Level 3: try the blanks from memory first, then check the bank.

1The side of a triangle used as the bottom for measuring area is the .
2The perpendicular distance from the base to the opposite vertex is the .
3The amount of flat space inside a triangle is its .
4Two lines that meet at a 90° angle are .
5A shape made of two or more basic shapes combined is a .
6A math rule written with symbols, like A = ½ × b × h, is a .

Write About the Math Guided ESOL writing

Use the support level you need. Every level answers the same math question.

1. Understand the Question

explain

Your triangular panel (base 12, height 8) fits inside a 12 by 8 rectangle. Why do we divide by 2 to find the triangle's area before cutting the glass?

Your job: Answer the question. Use math evidence. Explain how the evidence proves your answer.Responde la pregunta. Usa evidencia matemática. Explica cómo la evidencia demuestra tu respuesta.

2. Plan Your Math Words

Check at least two words you will use.

Base — A side of the triangle you use to find the area.Base — Un lado del triángulo que usas para hallar el área. Height — The straight-up distance from the base to the top corner.Altura — La distancia recta desde la base hasta la esquina de arriba. Area — How much space is inside a flat shape.Área — Cuánto espacio hay dentro de una figura plana. Perpendicular — Two lines that meet to make a square corner (90 degrees).Perpendicular — Dos líneas que se unen formando una esquina recta (90 grados). Formula — A math rule written with symbols.Fórmula — Una regla matemática escrita con símbolos.

Say it first: Say your idea to a partner or quietly to yourself before you write.Di tu idea a un compañero o en voz baja antes de escribir.

A triangle is half of a ___ with the same base and height.Un triángulo es la mitad de un ___ con la misma base y altura.

3. Build Your Explanation

Model the parts: This model shows the parts of an explanation. It does not answer your writing question.

Claim: The height is the perpendicular distance from the base to the top corner.

Evidence: Students identify the height as the perpendicular (straight-up, 90-degree) distance from the base to the opposite vertex, not the slanted side.

Reasoning: This evidence connects the definition of area to the mathematical claim.

Start

Most language support

Complete the frames. Use the word bank.Completa las oraciones. Usa el banco de palabras.

A triangle is half of a ___ with the same base and height.Un triángulo es la mitad de un ___ con la misma base y altura.
So the area is 1/2 times 12 times 8, which equals ___.Entonces el área es 1/2 por 12 por 8, que es ___.

Build

Some language support

Write two connected sentences. Use because, so, or but.Escribe dos oraciones conectadas. Usa porque, entonces o pero.

My claim is ___.Mi afirmación es ___.
I know because ___.Lo sé porque ___.
So ___.Entonces ___.

Explain

Light language support

Write a claim, give math evidence, and explain your reasoning.Escribe una afirmación, da evidencia matemática y explica tu razonamiento.

My claim is ___.Mi afirmación es ___.
My math evidence is ___.Mi evidencia matemática es ___.
This proves ___ because ___.Esto demuestra ___ porque ___.

4. Check Your Explanation

I answered the question.Respondí la pregunta. I used math evidence: numbers, an equation, a model, or a comparison.Usé evidencia matemática: números, una ecuación, un modelo o una comparación. I explained how the evidence proves my answer.Expliqué cómo la evidencia demuestra mi respuesta. I used at least two math words.Usé por lo menos dos palabras matemáticas. I reread complete sentences and punctuation.Volví a leer mis oraciones completas y la puntuación.