Lesson plan Grade 10 Science
Hollow Pine River: Streamflow Data and Earth-System Feedbacks
A grade 10 lesson where students analyze streamflow and sediment data around a fictional dammed river to identify Earth-system feedbacks and write a claim.
Objectives
- Students will analyze streamflow and sediment-load data to identify Earth-system feedbacks caused by a dam.
- Students will calculate percent change in average peak flow and average sediment load using before-and-after dam data.
- Students will construct a claim-evidence-reasoning explanation connecting one change in a river to a feedback in a different Earth system.
Vocabulary
- Streamflow
- Streamflow is the amount of water moving past a point in a river or stream in a given amount of time. It rises after storms and snowmelt and drops during dry spells.
Also: sediment transport, feedback, delta, groundwater recharge
Teacher overview
The fictional Hollow Pine River was dammed decades ago to store water and generate a small amount of hydroelectric power. This lesson gives students hypothetical five-year averages of the river's peak flow and sediment load from before and after the dam was built, and asks them to analyze how one change to Earth's surface, blocking sediment behind the dam, creates feedbacks in other systems downstream. A common misconception is treating a dam's effects as limited to the river itself; the data and discussion in this lesson are built to trace those effects into groundwater recharge, delta erosion, and channel shape.
Procedure
Hook (5 min): Show students a simple diagram or description of Hollow Pine Dam blocking the river, and ask them to predict, in pairs, what might change downstream in the years after a dam like this is built. Collect two or three predictions on the board without comment.
Direct instruction (15 min): Present the hypothetical Hollow Pine data table below and explain that one Earth-surface change, a dam trapping sediment, can create feedbacks that reach other Earth systems: reduced sediment delivery can starve river deltas and coastlines of the material that normally rebuilds them, while a river's altered flow pattern can change how much water infiltrates the streambed to recharge nearby groundwater. Model reading the "before dam" column and calculating the percent decrease in average peak flow (Question 1) using Percent decrease = (before − after) ÷ before × 100.
| Measurement | Before dam (5-yr average) | After dam (5-yr average) |
|---|---|---|
| Average peak flow (cfs) | 3,200 | 1,100 |
| Average sediment load (tons/day) | 850 | 90 |
Guided practice (15 min): In small groups, students calculate the percent decrease in average sediment load (Question 2) using the same percent-decrease formula, then identify two specific feedback effects the data suggests, such as a calmer, more sediment-starved river below the dam eroding its own banks to replace the sediment it no longer carries naturally. Circulate and check that groups can explain their reasoning, not just their arithmetic.
Independent practice (10 min): Each student writes a short claim-evidence-reasoning paragraph (Question 3) explaining one specific feedback caused by the sediment change, citing at least one number from the data table as evidence.
Closure / exit ticket (5 min): Students answer one question on an index card: "Name one Earth system, other than the river's flow itself, that is affected when a dam changes a river's sediment load, and explain how." Collect and scan responses for the correct mechanism, a sediment change causing an effect somewhere else, before dismissal.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
- Answer: 65.6 percent.
(3,200 − 1,100) ÷ 3,200 × 100 = 2,100 ÷ 3,200 × 100 = 65.63, which rounds to 65.6 percent decrease in average peak flow. - Answer: 89.4 percent.
(850 − 90) ÷ 850 × 100 = 760 ÷ 850 × 100 = 89.41, which rounds to 89.4 percent decrease in average sediment load. - Answer: model response.
A strong paragraph claims that the dam is starving the delta: average sediment load fell from 850 to 90 tons per day, an 89.4 percent decrease, so far less material reaches the river's mouth and the delta erodes faster than it is rebuilt. Bank and bed erosion below the dam, as the sediment-starved river picks up new material, is another reasonable claim.
Differentiation
Support (below grade level)
Provide the percent-decrease formula worked through with a labeled example unrelated to the data table before students calculate item 2 on their own, and allow calculators for all steps.
Extension (above grade level)
Ask students to propose one design solution, such as scheduled flow releases or a fish and sediment bypass channel, that could reduce Hollow Pine Dam's downstream sediment feedback without removing the dam, and explain what data they would want to collect to test whether it worked.
ELL supports
Pre-teach "sediment," "feedback," and "delta" with a simple labeled diagram showing a river, a dam, trapped sediment, and an eroding delta downstream. Allow students to complete the independent-practice paragraph as a labeled diagram with short captions instead of full sentences.