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Lesson plan Grade 6 English Language Arts

Brinewood Bay's Desalination Plant: A Grade 6 Writing Lesson

A 50-minute grade 6 lesson where students sequence reverse-osmosis process cards from a fictional coastal plant into an organized informative paragraph.

Objectives

  1. Students will organize information about a multi-step water treatment process into a clear informative paragraph.
  2. Students will use domain-specific vocabulary accurately when explaining how reverse osmosis removes salt from seawater.
  3. Students will select relevant details from a provided fact set rather than including everything they read.

Vocabulary

Reverse osmosis
Reverse osmosis cleans water by pushing it through a membrane with holes so tiny that salt and most other dissolved things cannot fit through. It can even turn seawater into fresh water.
Desalination
Turning salty water, like ocean water, into fresh water people can use. It works, but it takes a lot of energy and leaves behind very salty water that must be handled carefully.
Brine
The extra-salty water left over after desalination pulls fresh water out of seawater. Plants must dispose of it carefully so it does not harm sea life.

Also: membrane, intake

Teacher overview

The fictional coastal town of Brinewood Bay built a desalination plant that uses reverse osmosis to turn seawater into drinking water. Sixth graders often assume the process happens all at once, in a single mysterious step; this lesson breaks it into five distinct stages using sequenced fact cards, then asks students to organize those stages into an informative paragraph rather than a list. A common misconception this lesson addresses directly is that all of the seawater becomes drinking water; students must explain, using the process cards, that a concentrated leftover stream called brine is also produced and returned to the ocean.

Procedure

Hook (5 min): Ask students: "If you could turn ocean water into water you could drink, what steps do you think that would take?" Collect two or three guesses on the board without correcting them yet.

Direct instruction (10 min): Introduce Brinewood Bay, a fictional coastal town, and its desalination plant. Display five process cards in mixed order: Intake (seawater is pulled in through screened pipes), Pretreatment (sand, algae, and other particles are filtered out so they do not clog the membrane), High-Pressure Pump (the water is pushed at high pressure toward a membrane), Membrane (a reverse osmosis membrane blocks salt and other dissolved solids while clean water passes through; the salty water left behind, called brine, is piped back to the ocean), and Post-Treatment (minerals are added back and the water is disinfected before it enters the distribution system). Model reading one card aloud and thinking through where it belongs in the sequence.

Guided practice (15 min): In pairs, students arrange all five cards in the correct order and write one transition sentence connecting each card to the next, such as "After intake, the water moves to pretreatment, where..." Circulate and check that pairs place the membrane card correctly, since it is the step students most often misplace.

Independent practice (15 min): Each student drafts an informative paragraph of five to seven sentences explaining the reverse osmosis process at Brinewood Bay, using the five process-card facts in order and defining at least two vocabulary words, membrane and brine, within the paragraph itself.

Closure / formative check (5 min): Students trade paragraphs with a partner and complete a two-item checklist: does the paragraph explain what happens to the leftover salty water, and does the paragraph use the stages in the correct order? Collect a show of thumbs, up if both checklist items are met, before dismissal, and reteach the brine step to any table where fewer than half the students raise a thumb.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Checklist answer (stage order): The five stages in order are intake, pretreatment, high-pressure pump, membrane, and post-treatment.
  2. Checklist answer (leftover salty water): A complete paragraph must state that the concentrated salty water left behind, called brine, is returned to the ocean rather than becoming drinking water, since only the water that passes through the membrane becomes the plant's output.

Differentiation

Support (below grade level)

Provide sentence starters for each stage of the paragraph, such as "First, the plant pulls in seawater through ___. Next, ___," and reduce the paragraph requirement to three sentences covering intake, membrane, and post-treatment only.

Extension (above grade level)

Ask students to add a sixth sentence explaining what happens to the brine after it leaves the plant, drawing only from a teacher-provided card stating that concentrated brine is returned to the ocean through a diffuser designed to limit harm to marine life.

ELL supports

Pair each process card with a simple icon, such as a pipe, a filter, a pump, a membrane grid, and a faucet, so students can sequence the cards by image before attaching vocabulary. Allow the independent paragraph to be dictated aloud to a partner or recorded before being written down.