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Worksheet Grade 6 Math

Brandymoor Creek's Storm Gauge: Decimals and Rates of Rise

A grade 6 worksheet on a creek gauge read every two hours during a storm, with decimal subtraction, rates of rise and fall, and a flood-stage comparison.

Objectives

  1. Students will subtract decimal gauge readings to find the change in a creek's water level.
  2. Students will divide a decimal change by hours to state a rate of rise per hour.
  3. Students will compare rates to identify when a creek rose fastest during a storm.

Vocabulary

Flood stage
Flood stage is the water level in a river at which it starts to overflow its banks and cause flooding problems nearby. Forecasters compare the current water level to flood stage to warn people when flooding is about to happen.

Also: gauge, stage, rate

Teacher overview

A stream gauge reports how high the water stands, and a reader turns a column of those readings into a change over time to find how fast the water is moving up or down. This worksheet uses the fictional Brandymoor Creek, where a gauge was read every two hours through one storm day, and students subtract decimal readings and divide by hours to find how fast the creek rose and then fell. The set is built so that the largest single rise and the fastest rate belong to the same two-hour block, which gives students a check on their own arithmetic.

Brandymoor Creek's Storm Gauge: Decimals and Rates of Rise — Grade 6 Math
Name: ____________________________ Date: ______________

Student Worksheet

The table gives gauge readings from the fictional Brandymoor Creek on one storm day. The stage is the height of the water at the gauge, measured in feet. Flood stage at this gauge is 6.00 feet. Round any answer with more than three decimal places to the nearest hundredth.

Time Stage (feet)
6 a.m. 2.15
8 a.m. 2.60
10 a.m. 3.45
noon 4.80
2 p.m. 5.25
4 p.m. 4.90
6 p.m. 4.15
8 p.m. 3.40
  1. How many feet did the stage rise between 6 a.m. and 8 a.m.?
  2. That rise took 2 hours. What was the rate of rise in feet per hour?
  3. How many feet did the stage rise between 10 a.m. and noon?
  4. That rise also took 2 hours. What was the rate of rise in feet per hour?
  5. How many feet did the stage rise in all, from the 6 a.m. reading to the 2 p.m. peak?
  6. Those 8 hours brought the rise in item 5. What was the average rate of rise in feet per hour?
  7. How many feet did the stage fall from the 2 p.m. peak to the 8 p.m. reading?
  8. That fall took 6 hours. What was the rate of fall in feet per hour?
  9. The total rise in item 5 is given in feet. How many inches is that rise, if 1 foot is 12 inches?
  10. Flood stage is 6.00 feet. How far below flood stage was the 2 p.m. peak?
  11. Between which two readings did the creek rise fastest? Give the rate in feet per hour that shows it.

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: 0.45 foot.
    Subtract the earlier reading from the later one: 2.60 minus 2.15 is 0.45 foot.
  2. Answer: 0.225 foot per hour.
    Divide the rise by the hours: 0.45 divided by 2 is 0.225 foot per hour.
  3. Answer: 1.35 feet.
    Subtract 3.45 from 4.80, which gives 1.35 feet.
  4. Answer: 0.675 foot per hour.
    Divide the rise by the hours: 1.35 divided by 2 is 0.675 foot per hour.
  5. Answer: 3.10 feet.
    The peak reading is 5.25 and the first reading is 2.15, and 5.25 minus 2.15 is 3.10 feet.
  6. Answer: 0.39 foot per hour.
    From 6 a.m. to 2 p.m. is 8 hours, and 3.10 divided by 8 is 0.3875, which rounds to 0.39 foot per hour.
  7. Answer: 1.85 feet.
    Subtract the 8 p.m. reading from the peak: 5.25 minus 3.40 is 1.85 feet.
  8. Answer: 0.31 foot per hour.
    From 2 p.m. to 8 p.m. is 6 hours, and 1.85 divided by 6 is 0.3083, which rounds to 0.31 foot per hour.
  9. Answer: 37.2 inches.
    Multiply the feet by 12: 3.10 times 12 is 37.2 inches.
  10. Answer: 0.75 foot.
    Flood stage is 6.00 feet and the peak was 5.25 feet, and 6.00 minus 5.25 is 0.75 foot.
  11. Answer: Between 10 a.m. and noon, at 0.675 foot per hour.
    The four rising blocks give 0.225, 0.425, 0.675, and 0.225 foot per hour, and 0.675 is the largest of the four, so the creek rose fastest in the block from 10 a.m. to noon.

Differentiation

Support

Give these students a copy of the fictional creek's table with a blank third column headed "change from the reading above," and have them fill that column before answering anything. Assign items 1, 2, 3, 4, and 10, and let them use a number line marked in tenths of a foot to check each subtraction.

Extension

Ask these students to estimate when the fictional Brandymoor Creek would return to its 6 a.m. stage of 2.15 feet if it keeps falling at the rate found in item 8. They should show the number of feet still to fall, give the number of hours to the nearest tenth, and explain why a real creek usually falls more slowly than that estimate predicts.

ELL supports

Pre-teach stage, rise, fall, and flood stage with a drawing of a creek bank marked in feet and a labeled arrow for each word. Provide these sentence frames: "The stage went from ___ feet to ___ feet, so the change is ___ feet." and "The change took ___ hours, so the rate is ___ foot per hour."

Extensions

Have students plot the eight readings from the fictional Brandymoor gauge on graph paper with time on the horizontal axis and stage on the vertical axis, then mark the steepest section of their line. Comparing the steepest part of the graph with their answer to item 11 shows the class that a rate is visible as a slope, which is the reading skill the graphs in grade 7 and grade 8 will assume.