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Classroom activity Grade 6 Art & Music

Turbidity Value Scale: A Water-Testing Paint Station at Marsh Landing

A grade 6 art station where students paint a five-step light-to-dark value scale for water clarity and write short captions matching each swatch to a turbidity level.

Objectives

  1. Students will paint an ordered value scale from light to dark.
  2. Students will match each painted step to a level of water clarity.
  3. Students will write a short caption explaining what each level means.

Vocabulary

Turbidity
Turbidity is a measure of how cloudy or murky water looks because of tiny particles floating in it. Clear water has low turbidity, and muddy water has high turbidity.

Also: value scale, clarity, swatch, legend

Teacher overview

Turbidity is a measure of how cloudy water is, and testers judge it by how much light passes through a sample. Marsh Landing (a fictional water utility for this activity) wants a simple painted chart that helps visitors picture what "clear" and "cloudy" look like. In this art station, students mix a value scale, which is an ordered set of steps from light to dark, using one paint color thinned with different amounts of water. Each step becomes a swatch that stands for a level of clarity, from very clear water to very cloudy water. The activity teaches the art skill of controlling value, meaning lightness and darkness, while connecting it to a real testing idea: the cloudier the sample, the higher its turbidity, and in this chart a darker swatch stands for cloudier water. Students then write a short caption for each swatch so the finished chart reads as a legend.

Activity Directions

  1. Set up the station with paint, water cups, brushes, and heavy paper. Post the printed clarity legend, which lists five levels from "very clear" to "very cloudy."
  2. Demonstrate value control once: load the brush with paint for the darkest step, then add more and more water to make each next step lighter. Show that the same color can make five different values.
  3. Have students draw five equal boxes in a row on their paper and label them 1 to 5, with box 1 for the lightest and box 5 for the darkest.
  4. Students paint box 1 the palest wash, then paint each following box a step darker, ending with box 5 as the most opaque. Encourage even, flat washes so the steps look ordered.
  5. Once the swatches dry enough to write near, students add a one-sentence caption under each box that explains what that clarity level would mean for a water sample, using the legend as a guide.
  6. Students place their finished scale next to the legend and check that a classmate can point to any described clarity level and land on the right swatch.
  7. End the station when each student has five ordered swatches with five captions. Early finishers add a title bar to their chart.
  8. Debrief with two questions: how did adding water change the value of each swatch, and why is an ordered scale more useful to a visitor than a single painted sample?

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

Answer Key

Use this key for the ordering check. Students should be able to place the five swatches and captions in the correct order.

  1. Answer: Box 1, lightest, very clear. The palest swatch stands for water you can see straight through, the lowest turbidity.
  2. Answer: Box 3, middle value, slightly cloudy. A medium wash stands for water that is a little hazy but still lets some light through.
  3. Answer: Box 5, darkest, very cloudy. The most opaque swatch stands for water that blocks most light, the highest turbidity on the scale.

Differentiation

Support

Pre-draw the five boxes and pre-mix the darkest value so students only need to lighten each step. Provide caption sentence frames such as "This water is ___, which means ___."

Extension

Ask students to add a sixth swatch for a clarity level between two of their steps, explain how they mixed it, and write a caption that fits it correctly into the ordered legend.

ELL supports

Pre-teach "clear," "cloudy," "light," and "dark" by holding jars of clean and stirred-up water side by side. Allow captions to be short phrases, and let students point to the matching swatch as they say each caption aloud before writing it.