Fireworks in a Jar: Exploring Density and Mixtures

Name:

Date:

🔬 Part 1: Investigate

Learning Goal: I can use observations to explain how density affects a mixture of oil, water, and food coloring.

Science Idea: Oil and water do not mix. Oil is less dense than water, so it floats on top. Colored water droplets sink through the oil and then spread out in the water, making a fireworks-like pattern.

Safety Reminders: Work with adult supervision. Do not drink or taste any materials. Protect tables and clothing from spills.

Materials: clear jar, warm water, cooking oil, food coloring, dropper, paper towel, and tray or covered work surface.

1. Predict: What do you think will happen when food coloring is dropped into the oil?

2. Predict: Where do you think the food coloring will end up after a few minutes? Explain why.

Observation Steps:

1. Place the clear jar on a protected surface.

2. Carefully fill the jar about three-fourths full with warm water.

3. Slowly add oil, leaving a little space at the top. Wait until the layers settle.

4. Use the dropper to add several drops of food coloring to the oil.

5. Watch closely and record what happens at 0 minutes, 1 minute, and 3 minutes.

6. Clean up spills and return materials as directed.

Observation Table

Time

0 minutes

1 minute

3 minutes

What I see

Where the color is

✏️ Part 2: Explain Your Thinking

Vocabulary Match: Draw a line from each word to its meaning.

Words

1. density

2. mixture

3. dissolve

4. observe

Meanings

A. to watch carefully and notice details

B. how much matter is packed into a space

C. to become spread evenly into a liquid

D. two or more substances together that keep their own properties

3. Why does the oil stay above the water?

4. Why do the colored droplets sink through the oil?

5. Is the jar a mixture? Use evidence from your observations.

6. What evidence shows that oil and water do not mix?

7. How does the food coloring change as it reaches the water?

8. What might happen if the jar were shaken? Explain your prediction.

Claim-Evidence-Reasoning

Claim: What causes the fireworks-like pattern?

Evidence: Describe two observations from the investigation.

Reasoning: Use the words density and mixture to connect your evidence to your claim.

Writing and Math Connections: Use your recorded observations as evidence in your explanation. Record the time in minutes and compare how the mixture changes over time. CCSS.ELA-LITERACY.W.4.7; CCSS.MATH.CONTENT.4.MD.A.2

Exit Ticket

9. In one or two sentences, explain how density helps create the fireworks effect.

✅ Teacher Answer Key — Final Page

1. Answers will vary. A reasonable prediction is that the food coloring will sink through the oil.

2. The color will eventually move into and spread through the water because the colored droplets are water-based and water is denser than oil.

Vocabulary: 1-B, 2-D, 3-C, 4-A.

3. Oil stays above water because oil is less dense than water.

4. The colored droplets sink through the oil because the droplets are denser than the oil.

5. Yes. It is a mixture because oil, water, and food coloring are together but can still be seen as separate substances or layers.

6. The oil forms a separate layer and does not spread throughout the water.

7. The droplets sink, enter the water, and spread out or dissolve through it.

8. Shaking may temporarily mix the liquids into cloudy drops, but the oil and water will separate again when the jar rests.

9. Sample answer: Oil is less dense than water, so it floats. The denser colored water sinks through the oil and spreads in the water, creating the fireworks effect.

CER: Accept answers that state density causes the colored water to sink through the less-dense oil, cite observations such as sinking droplets and spreading color, and connect those observations to the claim.