Lesson plan Grade 2 Science
Bean Rows at the Fennhurst School Garden: A Watering Test
Grade 2 students plan a one-variable test of whether bean seedlings need water, measure heights with a centimeter ruler, and compare a watered row with a dry row.
Objectives
- Students will plan a garden test that changes only the water and keeps the light and soil the same.
- Students will measure bean seedlings in centimeters with a ruler and record each height on a chart.
- Students will use subtraction within 100 to compare growth in a watered row and a dry row.
Vocabulary
Key words: seedling, centimeter, row, compare, soil
Teacher overview
The garden club at the fictional Fennhurst School plants beans along the fence every spring, and one dry week is usually enough to cost the club a whole row. This lesson turns that loss into a planned test: one row of seedlings gets water every school day and one row gets none, with the light, the soil, and the pot size held the same. Expect a prediction that the unwatered row will stop growing the moment the watering stops, when in practice those seedlings gain a little height at first from the water already in the soil and then stall. The handout uses a recorded chart from an earlier class so that every student works from the same numbers.
Procedure
Session 1, setting the question (8 min): Show the class two bean seedlings, one from a pot that has been watered and one from a pot left dry for a week. Ask what is different and write the answers on the board. Steer the discussion toward a testable question: do bean plants need water to grow?
Session 1, planning the test (10 min): Ask what the class would have to keep the same for the test to be fair. Record the list on chart paper. The list should end with the same soil, the same pot size, the same window, and the same number of seeds, so that water is the only thing that changes between Row A and Row B.
Session 1, planting and labeling (12 min): Pairs plant three seeds each in the Row A tray and the Row B tray, then label both trays. Post the class rule where students can see it: water both trays until the seedlings are up, and from then on Row A gets one cup of water every school day and Row B gets none. Assign a daily waterer, and count the two weeks of the test from the day the seedlings are up.
Session 2, measuring day 14 (10 min): Two weeks after the seedlings come up, pairs measure their own seedlings from the soil line to the top leaf. Model the choice of tool first by holding up a yardstick and a centimeter ruler and asking which one fits a plant this small. Record each height on the class chart.
Session 2, working the handout (12 min): Students complete questions 1 through 6 using the recorded chart printed on the handout. Circulate and watch for students who write the day 14 height as the growth amount, which is the most common error at this grade because it skips the subtraction.
Session 2, closing claim (8 min): Ask for a show of hands on the question "Do bean plants need water to grow?" and then ask three volunteers to give one number from the chart as their reason. If fewer than three quarters of the class can name a number rather than a general impression, model one more comparison aloud before ending the lesson.
Student Handout
The garden club at Fennhurst School kept this chart last spring. Row A was watered every school day. Row B got no water. Imagine your class is checking the club's work.
| Plant | Row | Height on day 1 (cm) | Height on day 14 (cm) |
|---|---|---|---|
| Bean 1 | A, watered | 4 | 18 |
| Bean 2 | A, watered | 5 | 21 |
| Bean 3 | B, no water | 4 | 6 |
| Bean 4 | B, no water | 5 | 7 |
- Bean 1 was 4 cm tall on day 1 and 18 cm tall on day 14. How many centimeters did it grow?
- Bean 3 was 4 cm tall on day 1 and 6 cm tall on day 14. How many centimeters did it grow?
- Bean 2 was 5 cm tall on day 1 and 21 cm tall on day 14. How many centimeters did it grow?
- On day 14, Bean 2 was 21 cm tall and Bean 4 was 7 cm tall. How much taller was Bean 2?
- On day 14, Bean 1 was 18 cm tall and Bean 2 was 21 cm tall. What is the total of those two heights?
- Bean 3 grew 2 cm and Bean 4 grew 2 cm. What is the total growth of Row B?
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: 14 cm. Take the day 1 height from the day 14 height: 18 - 4 = 14.
- Answer: 2 cm. Take the day 1 height from the day 14 height: 6 - 4 = 2.
- Answer: 16 cm. Take the day 1 height from the day 14 height: 21 - 5 = 16.
- Answer: 14 cm. Compare the two day 14 heights: 21 - 7 = 14.
- Answer: 39 cm. Add the two day 14 heights: 18 + 21 = 39.
- Answer: 4 cm. Add the two growth amounts: 2 + 2 = 4.
Differentiation
Support
Give these students a handout with the subtraction already set up in vertical form so that only the computation remains, and let them use a centimeter ruler as a number line for counting up from the smaller height to the larger one.
Extension
Ask students to predict, in writing, what the Row B heights would be on day 28 if the club still gave no water, then defend the prediction with two numbers from the chart. Accept any prediction that stays at or very near the day 14 heights and cites the small growth already recorded.
ELL supports
Pre-teach "soil," "seedling," and "row" with the real trays in hand, pointing to each as it is named. Provide the sentence frame "Bean ___ grew ___ centimeters because ___" for the closing claim, and allow students to answer questions 1 through 6 with numbers alone.
Extensions
Two weeks after the lesson, water Row B for one week and measure again. Students then argue in writing whether the dry plants recovered, which sets up the idea that a plant deprived of water for too long may not come back even when watering resumes.