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Classroom activity Grade 6 Math

Junction Creek Sampling Stations: A Percent-in-Range Game

A grade 6 math station-rotation activity where groups read fictional water-test cards and calculate what percent of each station's readings fall in the safe range.

Objectives

  1. Students will count how many test readings fall inside a safe range at each station.
  2. Students will convert each station's in-range count to a percent and compare the four stations.

Vocabulary

Key words: sample, safe range, percent, water quality

Teacher overview

This is a small-group station rotation for groups of three to four students. Four station cards sit around the room, each holding five water-test readings from one monitoring point on the creek or the town water system. The math a group does at each card, counting how many readings land in the safe range and turning that into a percent, mirrors how a utility reports whether a site is in compliance. Junction Creek is a fictional stream created for this activity, though the safe ranges come from real benchmarks. Students move from station to station and compute each site's percent in range, just as monitoring crews check site after site.

Activity Directions

  1. Before class, print the four station cards and place them at four spots around the room. Each card names a test, its safe range, and five readings. The safe ranges are drawn from real benchmarks: pH from 6.5 to 8.5, dissolved oxygen above 5 mg/L, chlorine from 0.2 to 2.0 mg/L, and turbidity at or below 0.3 NTU. The chlorine and turbidity ranges apply to treated drinking water, not creek water, so those two cards come from the town's water system. Chlorine that reaches a creek harms fish.
  2. Put students in groups of three to four and give each group a recording sheet. Assign each group a different starting station so the groups spread out.
  3. At each station, the group reads the five readings on the card and decides which readings fall inside the safe range. They record the in-range count out of five.
  4. The group then converts that count to a percent of the five readings and writes it on the recording sheet.
  5. On your signal, groups rotate to the next station. Give about four minutes per station so every group visits all four.
  6. The game ends when every group has visited all four stations and filled in a percent for each. Gather the class for the debrief.
  7. Debrief with two questions: which station had the highest percent in range, and why does turning counts into percents let a utility compare stations that were each sampled five times? Tie the answers back to the numbered questions on the handout.
Junction Creek Sampling Stations: A Percent-in-Range Game — Grade 6 Math
Name: ____________________________ Date: ______________

Student Handout

Suppose the fictional town of Junction has four sampling stations: two on Junction Creek and two in the town's treated-water system. Each station was tested five times. Read the readings at each station and answer the questions. A reading counts as in range only if it falls inside the safe range given.

  1. Station 1 tested pH: 7.0, 8.0, 9.0, 6.8, and 7.5. The safe range is 6.5 to 8.5. How many readings are in range?
  2. What percent of Station 1's five readings are in range?
  3. Station 2 tested oxygen in mg/L: 6.0, 4.0, 7.0, 5.5, and 3.0. Safe is above 5 mg/L. How many readings are in range?
  4. What percent of Station 2's five readings are in range?
  5. Station 3 is a tap on the town's treated-water pipes and tested chlorine in mg/L: 0.5, 1.0, 2.5, 0.1, and 1.5. Safe is 0.2 to 2.0 mg/L. How many readings are in range?
  6. What percent of Station 3's five readings are in range?
  7. Station 4 is the water plant's filter outlet and tested turbidity in NTU: 0.1, 0.2, 0.4, 0.3, and 0.5. Safe is at or below 0.3 NTU. How many readings are in range?
  8. What percent of Station 4's five readings are in range?
  9. Which station had the highest percent in range?
  10. A station passes only if at least 90 percent of its readings are in range. Did any station pass?

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: 4 readings. The range is 6.5 to 8.5; the 9.0 reading is out, so 7.0, 8.0, 6.8, and 7.5 are in range.
  2. Answer: 80%. 4 of 5 readings are in range: 4 ÷ 5 = 0.80, or 80 percent.
  3. Answer: 3 readings. Above 5 mg/L means 6.0, 7.0, and 5.5 count; 4.0 and 3.0 are out.
  4. Answer: 60%. 3 of 5 readings are in range: 3 ÷ 5 = 0.60, or 60 percent.
  5. Answer: 3 readings. In 0.2 to 2.0 mg/L, the readings 0.5, 1.0, and 1.5 count; 2.5 and 0.1 are out.
  6. Answer: 60%. 3 of 5 readings are in range: 3 ÷ 5 = 0.60, or 60 percent.
  7. Answer: 3 readings. At or below 0.3 NTU, the readings 0.1, 0.2, and 0.3 count; 0.4 and 0.5 are out.
  8. Answer: 60%. 3 of 5 readings are in range: 3 ÷ 5 = 0.60, or 60 percent.
  9. Answer: Station 1. Its 80 percent is higher than the 60 percent at each other station.
  10. Answer: No. The highest was 80 percent, which is below the 90 percent a station needs to pass.

Differentiation

Support

Give supported groups a recording sheet with the "out of 5" already printed and a checkbox beside each reading, so students mark in or out before counting. Pre-mark one station as a worked example. Allow a calculator for the percent step.

Extension

Ask groups to design a fifth station with exactly 40 percent of its readings in range, choosing five readings and a safe range that produce that result, then trade cards with another group to check.

ELL supports

Pre-teach reading, range, in range, and pass with a number line that shades the safe band. Pair each new term with a short home-language phrase. Provide a sentence frame for the debrief: "Station ___ had the highest percent because ___."