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Worksheet Grade 5 Science

Marbleton's Six Steps: A Grade 5 Treatment Flow Worksheet

Students put the six steps of the fictional Marbleton water plant in order, explain what each one removes, and convert settling and filter times into minutes.

Objectives

  1. Students will place the six steps of a drinking water plant in the order water passes through them.
  2. Students will explain what each treatment step removes from the water.
  3. Students will convert a holding time from hours to minutes and add two holding times.

Vocabulary

Coagulation
Coagulation is the first cleaning step at a drinking water plant. Operators quickly mix in a chemical that makes tiny bits of dirt stop pushing each other away so they can start sticking together.
Clearwell
A clearwell is a large storage tank at a treatment plant that holds finished water right after it comes out of the filters. It gives the disinfectant enough time to work before the water is pumped out to homes and businesses.

Also: screening, settling, filter, disinfect

Teacher overview

The fictional town of Marbleton draws its drinking water from the Halcott River and sends it through six steps before any of it reaches a faucet. This worksheet has students put those steps in order, say what each one takes out, and work with the times the water spends in two of them. A common error in this unit is treating the filter as the step that makes water safe to drink; the filter removes particles that can be caught in sand, while germs small enough to slip through are handled at the disinfection step that follows. Items 4 and 5 are written to separate those two jobs. The worksheet names the steps in plain language, and two of them have technical names an operator would use: the mixing step is called coagulation, and the covered tank that holds the finished water is called the clearwell.

Marbleton's Six Steps: A Grade 5 Treatment Flow Worksheet — Grade 5 Science
Name: ____________________________ Date: ______________

Student Worksheet

At the Marbleton plant, river water passes through six steps. Here are the six steps, listed out of order:

filtering, screening, storage, settling, mixing, disinfecting

  1. Write the six steps in the order the water goes through them at the plant, from the river to the storage tank.
  2. One step uses a metal screen at the river intake. It catches sticks, leaves, and fish before they reach the plant. Which step is it?
  3. In the mixing step, the plant stirs in a chemical that makes tiny bits of dirt clump together into bigger clumps. Explain why bigger clumps are easier to take out of the water than tiny bits.
  4. In the settling step, heavy clumps sink to the bottom of a large basin. Explain why the plant settles the water before it sends the water to the filter.
  5. Some germs are too small to be caught by the filter. Which step handles those germs, and what does that step do?
  6. Water sits in the Marbleton settling basin for 2 hours. How many minutes is that?
  7. At Marbleton, water sits in the settling basin for 120 minutes and then spends 20 minutes in the filter. How many minutes does the water spend in those two steps together?
  8. After treatment, Marbleton holds the clean water in a covered storage tank until homes need it. Explain why the plant keeps treated water in a tank instead of sending all of it straight to houses.
  9. Marbleton tests the water once after settling and again after filtering. Explain why testing at two steps tells the operator more than testing only at the end.
  10. Marbleton also pays farmers upstream to put fences along the Halcott River so cattle stay out of the water. Explain how those fences make the plant's job easier.

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: Screening, mixing, settling, filtering, disinfecting, storage. Water is screened at the intake, mixed with a clumping chemical, settled in a basin, passed through a filter, disinfected, and then held in storage.
  2. Answer: Screening. The screen at the intake stops sticks, leaves, and fish before the water enters the plant.
  3. Answer: Bigger clumps are heavier than tiny bits, so they sink faster in a settling basin and are also easier for a sand filter to trap.
  4. Answer: Settling drops out most of the heavy clumps first, so the filter does not clog as quickly and can catch the smaller bits that are left.
  5. Answer: Disinfecting. The plant adds a small amount of chlorine, which kills or inactivates germs that are too small for the filter to catch.
  6. Answer: 120 minutes. One hour is 60 minutes, so 2 hours is 2 times 60, which equals 120 minutes.
  7. Answer: 140 minutes. Add the two times: 120 minutes in the basin plus 20 minutes in the filter equals 140 minutes.
  8. Answer: The tank holds a supply that is ready when many people use water at once, such as in the morning, so the plant does not have to speed up and slow down all day. Accept any answer describing stored water meeting changing demand.
  9. Answer: Testing at two steps shows the operator which step is working and which one is not. If the water is still cloudy after settling but clear after filtering, the operator knows the settling basin needs attention.
  10. Answer: Cattle standing in the river stir up mud and leave waste in it, so fencing them out means less dirt and fewer germs arrive at the intake, and the plant uses less chemical and less filter time to clean the same water.

Differentiation

Support

Give these students the six step names printed on cut-apart strips so item 1 becomes a sorting task instead of a writing task. For item 6, provide the sentence "1 hour = 60 minutes" at the top of the page and let them use a calculator.

Extension

Ask these students to write one more step that the Marbleton plant could add, name where it would go in the order, and explain what problem it would solve. Have them compare their new order to the plant's six steps.

ELL supports

Provide a labeled flow diagram of the plant with a picture beside each of the six step names, and read items 3 through 5 aloud. Accept short phrases such as "kills germs" for item 5, and allow students to point to the diagram when explaining their answers to items 4 and 8.

Extensions

Have students look up the treatment steps their own utility uses, from a printed water quality report the teacher supplies, and compare that list to the six steps used in the town of Marbleton. Ask them to note any step their utility has that Marbleton does not, such as softening or adding fluoride.