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Worksheet Grade 9 Art & Music

A Calder Creek Water-Quality Dashboard: Grade 9 Value-Ramp Worksheet

Grade 9 art and data worksheet where students design an accessible value-ramp status dashboard and match displayed precision to instrument limits.

Objectives

  1. Students will assign a value ramp so darker shades match higher, less desirable readings.
  2. Students will add icons and labels so a dashboard stays readable without color alone.
  3. Students will report readings at the precision their instrument actually supports.

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.
Chlorine residual
Chlorine residual is the small amount of chlorine still left in the water after it leaves the treatment plant. It keeps protecting the water from germs all the way to your faucet.

Also: value ramp, precision, diverging scale, accessibility

Teacher overview

More utilities now post a public dashboard that shows current water-quality readings at a glance. A dashboard is a design object, and small choices about color, shade, icons, and how many digits to display decide whether a resident reads it correctly. This worksheet has students design and repair the status display for a fictional plant, using a light-to-dark value ramp that matches meaning, redundant coding that works for colorblind readers, and a level of precision that never claims more accuracy than the instrument can measure.

A Calder Creek Water-Quality Dashboard: Grade 9 Value-Ramp Worksheet — Grade 9 Art & Music
Name: ____________________________ Date: ______________

Student Worksheet

The fictional Calder Creek Water Plant posts a public dashboard with three signals. Use these dashboard bands for the items below.

  • Turbidity (NTU): Good is 0.00 to 0.15, Watch is 0.16 to 0.30, and Action is above 0.30.
  • Chlorine residual (mg/L): Good is 0.2 to 2.0, and Action is below 0.2.
  • pH: a healthy middle range with problems at both the low and the high end.
  1. On a light-to-dark value ramp for turbidity, should clearer water read lighter or darker, and why?
  2. The dashboard uses color to show status. Give one reason color alone is not enough, and name what to add so every reader can tell the bands apart.
  3. A turbidity reading of 0.30 NTU comes in. Using the bands above, which status does it get, Watch or Action?
  4. Finished water must stay at or below 0.3 NTU in 95 percent of monthly samples and never exceed 1 NTU. Explain why the dashboard sets its Action threshold right at 0.3 NTU.
  5. The turbidity meter reads to the nearest 0.01 NTU. How many decimal places should the dashboard show, and why not more?
  6. A chlorine test kit reads to the nearest 0.1 mg/L. A technician writes down 1.24 mg/L. Rewrite that value at the kit's precision.
  7. A chlorine residual of 0.1 mg/L appears on the dashboard. Which status is that, and what does a low residual risk in the pipes?
  8. List the three channels the dashboard should use together so status is clear to every reader.
  9. Explain why a single light-to-dark ramp does not fit pH, and name the kind of scale that fits a measure with a healthy middle.
  10. Explain why matching the dashboard's displayed precision to the instrument matters for public trust.

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. Answer: Clearer water should read lighter. The ramp should map higher turbidity, which means murkier water, to darker shades so the picture matches the meaning.
  2. Answer: Colorblind readers may not tell the hues apart, so the dashboard should add an icon or shape and a text label to each band.
  3. Answer: Watch. The Watch band runs to 0.30, and Action is only above 0.30, so a reading of exactly 0.30 stays in Watch.
  4. Answer: Setting the Action threshold at 0.3 NTU lines the public signal up with the regulatory level, so an Action reading flags a sample above the 0.3 NTU level that at least 95 percent of monthly samples must meet.
  5. Answer: Two decimal places, to match the meter's 0.01 NTU precision. Showing more digits would claim accuracy the instrument does not have.
  6. Answer: 1.2 mg/L. The kit reads to the nearest 0.1 mg/L, so 1.24 is rounded to 1.2.
  7. Answer: Action, because 0.1 is below the 0.2 Good threshold. A low residual risks leaving too little disinfectant to protect water as it travels through the pipes.
  8. Answer: Color from the value ramp, an icon or shape, and a text label, used together.
  9. Answer: pH is healthy in the middle and a problem at both ends, so a one-direction ramp cannot show it. A diverging scale, dark at both extremes and light in the middle, fits better.
  10. Answer: Showing more digits than the instrument can measure implies false accuracy, which can mislead residents, so matching precision keeps the dashboard honest and trustworthy.

Differentiation

Support

Provide a printed gray value strip and let students place the three turbidity bands on it before they answer item 1, so the ramp is concrete. Give the precision items a worked example, such as rounding 0.37 to one decimal, before items 5 and 6.

Extension

Ask students to design the full pH signal using a diverging scale, choosing shades for five bands from very low to very high, and to write a short caption telling a resident what each end means.

ELL supports

Provide a labeled diagram of a value ramp and a diverging scale with a home-language gloss where possible. Offer sentence frames such as "Clearer water should be ___ because ___." Allow students to shade sample swatches to answer the ramp items instead of writing full sentences.

Extensions

Students can find a real public water or air-quality dashboard, evaluate its value ramp, redundant coding, and displayed precision, and propose one specific improvement supported by the reasoning they practiced here.