Lab / experiment Grade 2 Science

Sunny Windowsill, Shady Shelf: A Grade 2 Ice Melting Investigation

Grade 2 students measure two identical ice pucks with a ruler as they melt in sun and shade, then refreeze the water to test whether the change reverses.

Grade: Grade 2
Subject: Science
Material: Lab / experiment
Time: 40 min
Prep: Moderate prep
Materials: 2 identical small paper cups per group, frozen solid the day before (same amount of water in each), Ruler marked in inches (1 per group), Clock or timer visible to the class, Tray or plate to catch melted water (2 per group), Access to a freezer, Paper towels, Data sheet or science journal

Standards

2-PS1-4 NGSS

Construct an argument with evidence that some changes caused by heating or cooling can be reversed and some cannot.

How this material aligns: Students argue, using their own melting and refreezing data from the Data & Analysis section, whether ice-to-water is a change that heating and cooling can reverse.

All materials for 2-PS1-4 →

2-ESS2-3 NGSS

Obtain information to identify where water is found on Earth and that it can be solid or liquid.

How this material aligns: The investigation has students handle and describe the same puck of water as a solid and then a liquid, the core observation this standard asks students to obtain.

All materials for 2-ESS2-3 →

Download Word file

This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-15.

Objectives

Students will measure the diameter of a melting ice puck in inches at set time intervals.
Students will compare melting in a sunny spot and a shady spot using their own measurements.
Students will construct an argument, using evidence, that freezing and melting are changes that can be reversed.

Teacher overview

Ice is one of the clearest examples of water changing from a solid to a liquid and back again. In this investigation, students freeze two identical ice pucks ahead of time, place one on a sunny windowsill and one on a shaded shelf, and measure how each one shrinks as it melts. At the end, they put both cups of melted water back into the freezer overnight and check whether it turns to ice again, building firsthand evidence that this change can be reversed.

Sunny Windowsill, Shady Shelf: A Grade 2 Ice Melting Investigation — Grade 2 Science

Name: ____________________________ Date: ______________

Procedure

Step 1 (advance prep). The day before, the teacher freezes two matching cups of water overnight. Each group gets two ice pucks. Both pucks start out the same size.

Step 2. Pop each frozen puck out of its cup onto a tray. Put one tray on a sunny windowsill. Put the other tray on a shady shelf.

Step 3. Before the timer starts, measure across each puck with a ruler. Write both starting sizes in the data table next to "0 minutes."

Step 4. Set the timer for 5 minutes. When it rings, measure both pucks again. Write the new sizes in the table. Safety note: hold the ruler, not the ice. Cold ice can feel like it burns if you hold it too long.

Step 5. Do step 4 three more times. Your class will measure at 0, 5, 10, 15, and 20 minutes.

Step 6. After 20 minutes, pour the water from each tray into a labeled cup, Sunny or Shady. Put both cups in the freezer overnight.

Step 7. The next day, look at both cups before you touch them. Write in the table whether each cup is frozen, part-frozen, or still liquid.

Data & Analysis

Time (minutes)	Sunny puck width (inches)	Shady puck width (inches)
0
5
10
15
20
Next day: frozen, part-frozen, or liquid?

Look at your data. How many inches smaller was the sunny puck at 20 minutes than at 0 minutes?
Look at your data. How many inches smaller was the shady puck at 20 minutes than at 0 minutes?
Which puck got smaller by more inches: the sunny puck or the shady puck?
Which spot melts ice faster: the sunny windowsill or the shady shelf? Use your measurements to explain your answer.
What happened to the melted water after one night in the freezer?
Is melting ice a change that can be reversed, or a change that cannot be reversed? Give one piece of evidence from your own test.
Suppose a sunny puck measured 3 inches at 0 minutes and 1 inch at 20 minutes. How many inches smaller did it get?

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: Answers will vary based on each group's actual measurements; the value should equal the puck's width at 0 minutes minus its width at 20 minutes, and it should be a positive number showing the puck got smaller. A difference of 0 inches is also acceptable when the group's measurements show it, since a puck that shrank by less than half an inch can round to the same whole inch.
Answer: Answers will vary in the same way as question 1, using the shady puck's own measurements.
Answer: In most classrooms, the sunny puck will show the larger change, since warmth from sunlight speeds up melting. Accept the shady puck's answer if a group's own data genuinely shows that result, as long as it is supported by their measurements.
Answer: A sunny windowsill melts ice faster than a shady shelf, because warmer surroundings add more heat to the ice. Accept any answer consistent with the group's own data and reasoning.
Answer: The melted water froze solid again (or partly froze), showing the liquid water turned back into a solid overnight in the freezer.
Answer: Melting ice into water is a reversible change. Strong evidence includes that the same water that melted in the trays froze solid again overnight, showing the change can happen in both directions.
Answer: 2 inches. 3 inches minus 1 inch equals 2 inches.

Differentiation

Support (below grade level)

Provide a pre-drawn number line from 0 to the largest expected diameter so students can count back to find the difference in questions 1 and 2 instead of subtracting on paper. Complete the first row of the data table together as a class demonstration before groups measure independently.

Extension (above grade level)

Ask students to predict, before starting the timer, which puck will finish melting first and explain their prediction using what they already know about sunlight and warmth. After the investigation, have them write two sentences comparing their prediction to what actually happened.

ELL supports

Pair the words "melt," "freeze," "sunny," and "shady" with simple picture cards (a sun, a shaded window, an ice cube, a puddle) posted near each station. Allow students to answer question 4 by pointing to the correct picture card and saying the matching word rather than writing a full sentence.