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Sunlight, Water, or Both

A 50-minute Grade 2 lesson on planning and running an investigation into whether plants need sunlight and water.

Sunlight, Water, or Both is a free 50-minute Grade 2 science lesson plan for Common Core standard 2-LS2-1 — test whether plants need sunlight and water to grow. It is timed across 5 sections, gives the exact wording to use where the wording carries the mathematics, names 3 misconceptions with the teaching move that addresses each, and ends with an exit ticket and a printable worksheet with its answer key.

Grade:
Grade 2
Length:
50 minutes
Standard:
2-LS2-1

Grade 2 · Life Science

2-LS2-1

Plan and conduct an investigation to determine if plants need sunlight and water to grow.

Objective

Students will be able to plan a four-tray investigation that changes one thing at a time.

Students are successful when they can

  • Names what is kept the same across the trays.
  • Names what differs between each pair.
  • Says what result would show a need.

What you need

  • Four seed trays, grass seed, the same soil, a cupboard and a windowsill
  • Labels and a watering measure
  • The printable practice sheet linked at the end of this plan

The lesson

Warm-up — one tray is not enough

5 min
  1. Show one tray of grass that grew well with light and water.
  2. Ask what it proves about sunlight. Nothing yet.

Teach — four trays, two things

13 min
  1. Set up tray 1 with sunlight and water, and tray 2 with sunlight and no water.
  2. Ask what the difference between those two would tell you. Whether water matters.
  3. Set up tray 3 with water and no sunlight, and tray 4 with neither.
  4. Ask what tray 4 is for. Something to compare the others against.
  5. List what stays the same: same seed, same soil, same trays, same day.
  6. Say what result would show a need: nothing grows when it is missing.
“What is different between these two trays, and only these two?”

Investigate — set them up

17 min
  1. Groups sow four trays with the same seed and soil on the same day.
  2. They label each tray with what it will get.
  3. They agree how much water the watered trays get and write it down.
  4. They write a prediction for each tray before leaving them.

Independent practice

12 min
  1. Students complete the 'Sunlight, Water, or Both' page.
  2. Check answers name what was kept the same.

Close

3 min
  1. Agree the day the class will measure, and what will be measured.

What goes wrong, and why

Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.

Changes water and light between the same two trays.

Why: It seems to test both at once.

Fix: Then no result can be explained. Change one thing per comparison.

Thinks tray 4 is a waste.

Why: Nothing will grow in it.

Fix: That is the point. It is what the others are compared against.

Waters by eye.

Why: It is quicker.

Fix: Write down the measure. Otherwise the amount is a second difference.

If they are not there yet

  • Two trays: with water and without.
  • Labels pre-written for each tray.

If they finish early

  • Add a fifth tray that tests whether soil is needed.
  • Say what you would measure to compare trays 1 and 3.
  • Predict what tray 3 would do if moved to the light.

Exit ticket

Tray 1 had sunlight and water; tray 2 had sunlight and no water. What does comparing just those two tell you?

What to look for: Whether water is needed, because that is the only difference. Naming both light and water means the one-thing rule needs another run.

Printable practice for 2-LS2-1

Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.

Questions about Sunlight, Water, or Both

How long does the Sunlight, Water, or Both lesson take?

50 minutes, split across 5 timed sections: warm-up 5 min, teach 13 min, investigate 17 min, independent practice 12 min, close 3 min. The minutes are stated per section and add up to the stated length, so the plan can be cut or extended at a section boundary rather than abandoned halfway.

Which standard does Sunlight, Water, or Both teach?

2-LS2-1 — 2-LS2-1, Life Science for Grade 2: “Plan and conduct an investigation to determine if plants need sunlight and water to grow.” In plain terms, test whether plants need sunlight and water to grow.

What do I need to teach this lesson?

Four seed trays, grass seed, the same soil, a cupboard and a windowsill, labels and a watering measure and the printable practice sheet linked at the end of this plan. Everything listed is either ordinary classroom equipment or a free printable from this site — there is nothing to buy and nothing to prepare beyond photocopying.

What mistakes should I expect in this lesson?

Three, each a reasoning error rather than carelessness: changes water and light between the same two trays; thinks tray 4 is a waste and waters by eye. The plan gives the thinking behind each one and the teaching move that addresses the thinking rather than the symptom.

How do I know whether the lesson worked?

The exit ticket asks: “Tray 1 had sunlight and water; tray 2 had sunlight and no water. What does comparing just those two tell you?.” Whether water is needed, because that is the only difference. Naming both light and water means the one-thing rule needs another run. That tells you whether the class needs a reteach or a thirty-second conversation before you plan tomorrow.

Is there a worksheet to go with Sunlight, Water, or Both?

Yes — 1 printable 2-LS2-1 worksheet, linked at the end of the plan and free like the rest of the site. Each one comes with an answer key and 25 versions, so the practice after the lesson can be a different paper on every desk.

Is Sunlight, Water, or Both free to use?

Yes. The plan, its printables and their answer keys are free to read, print and photocopy for your own class, with no account and no email capture. It was last reviewed on 8 September 2026. Please do not resell it or republish it as your own.

Last reviewed 2026-09-08. Aligned to 2-LS2-1 of the Next Generation Science Standards.