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Lesson plan Grade 6 Science

Ardenmill's Incoming Front: Weather Data and Reservoir Inflow

A 50-minute grade 6 lesson in which students read a day of Ardenmill weather station data, track a passing cold front, and estimate the reservoir inflow it produced.

Objectives

  1. Students will identify the pressure, temperature, and wind changes that mark the passage of a cold front.
  2. Students will total a column of rainfall readings and use a given rate to estimate reservoir inflow.
  3. Students will explain why the heaviest rain of a front arrives near the pressure minimum.

Vocabulary

Key words: air mass, cold front, barometric pressure, inflow

Teacher overview

A utility that draws from a surface reservoir watches the weather for a practical reason, since every storm that crosses the watershed becomes inflow a day or two later. In this lesson students read a single day of readings from the weather station in the town of Ardenmill, identify the moment a cold front passed, and convert the day's rainfall total into an estimate of reservoir inflow. The misconception this lesson corrects is that a falling barometer measures how much rain will fall. Students often read the pressure column as a rain gauge, when the falling pressure signals only that a low-pressure system is arriving, and the rain column has to be read on its own.

Procedure

Hook (5 min): Project the first two rows of the Ardenmill station record, showing 9 a.m. and 11 a.m. only, and ask students to predict whether it will rain that afternoon and to say what in the two rows supports the prediction. Record two or three predictions on the board without comment.

Direct instruction (12 min): Define air mass, cold front, and barometric pressure. Using the projected wall map, sketch a warm air mass sitting over the town of Ardenmill with a cooler air mass pushing in from the northwest. Explain the four signs of a front passing at a station: pressure falls and then rises, temperature drops, wind direction shifts, and rain arrives near the pressure low. Model reading one row of the record aloud, naming each column and its units.

Guided practice (13 min): Hand out the station record. Working in pairs, students highlight the row with the lowest pressure and the row with the largest temperature drop, then mark on their copy where they believe the front crossed the station. Circulate and ask two pairs to justify their mark using two different columns.

Independent practice (15 min): Students complete the five questions on the Student Handout individually. Announce that question 4 uses a rate, and remind students to find the day's rainfall total first.

Closure and formative check (5 min): Ask every student to hold up one, two, or three fingers for the two-hour window in which the front crossed, using 1 for the 1 p.m. reading, 2 for the 3 p.m. reading, and 3 for the 5 p.m. reading. If fewer than three quarters of the class holds up 3, reread the wind and temperature columns together before moving on.

Ardenmill's Incoming Front: Weather Data and Reservoir Inflow — Grade 6 Science
Name: ____________________________ Date: ______________

Student Handout

The weather station in the town of Ardenmill reported the readings below on one August day. Ardenmill Reservoir gains about 2 million gallons of inflow for every tenth of an inch of rain that falls on its watershed. Use the table to answer the questions.

Time Pressure (millibars) Temperature (degrees F) Wind from Rain since last reading (inches)
9 a.m. 1014 72 south 0.0
11 a.m. 1010 75 south 0.0
1 p.m. 1006 77 southwest 0.1
3 p.m. 1002 78 southwest 0.6
5 p.m. 1005 66 northwest 0.9
7 p.m. 1009 61 northwest 0.1
9 p.m. 1013 58 northwest 0.0
  1. The pressure was 1014 millibars at 9 a.m. and 1002 millibars at 3 p.m. How many millibars did the pressure fall between those two readings?
  2. Add the rain column for the whole day. How many inches of rain fell in all?
  3. The temperature was 78 degrees at 3 p.m. and 66 degrees at 5 p.m. How many degrees did the temperature fall between those two readings?
  4. Ardenmill Reservoir gains about 2 million gallons of inflow for every tenth of an inch of rain. Using your day total from question 2, how many million gallons of inflow should the reservoir expect?
  5. Between 3 p.m. and 5 p.m. the wind shifted from southwest to northwest, the temperature fell, and the pressure began to rise. Explain what those three changes together tell you about the air mass over Ardenmill.

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: 12 millibars.
    Subtract the later reading from the earlier one: 1014 - 1002 = 12 millibars.
  2. Answer: 1.7 inches.
    Add the rain column in order, so 0.0 plus 0.0 plus 0.1 plus 0.6 plus 0.9 plus 0.1 plus 0.0 gives 1.7 inches.
  3. Answer: 12 degrees.
    Subtract the later reading from the earlier one: 78 - 66 = 12 degrees.
  4. Answer: 34 million gallons.
    There are 17 tenths of an inch in 1.7 inches, since 1.7 divided by 0.1 is 17. Multiply by the rate: 17 x 2 = 34 million gallons.
  5. Answer: A cold front passed, and cooler air moved in behind it.
    Look for two of these three ideas: the cool air mass replaced the warm one, the wind shift marks the boundary crossing the station, and rising pressure means the low has moved east. Accept any answer naming a front or a change of air mass and citing at least one column as evidence.

Differentiation

Support

Give students a copy of the record with the rain column already circled and the running total partly filled in through the 3 p.m. row, so question 2 becomes a two-step addition. Provide a completed example of the rate step in question 4 using a different day in Ardenmill, such as 0.5 inches producing 10 million gallons.

Extension

Ask students to write the forecast the operator at the Ardenmill plant should post for the next morning, using the 7 p.m. and 9 p.m. rows as evidence, and to explain why the reservoir may keep rising for a day after the rain has stopped.

ELL supports

Pre-teach "air mass," "front," and "pressure" using a two-color diagram of cool air wedging under warm air. Provide a labeled version of the table header in each student's home language where possible, and give sentence frames for question 5, such as "The wind changed from ___ to ___, which shows that ___."

Extensions

Have the class track the school weather station or a public station near your town for one week, record the same five columns, and mark any day that shows the full set of front signs. Comparing that week with the Ardenmill record gives students a second data set for the same reasoning.