MnSTEP Teaching Activity Collection > MnSTEP Activities > Who is on Top?

# Who is on Top?

#### Summary

Student will determine which substance has a higher density: oil or water.

## Learning Goals

This activity is designed for students to investigate an unknown situation, make observations, and share data orally.

## Context for Use

This activity is intended for middle school-aged students. This can be used as introduction or exploring activity at the beginning of density unit study.

Subject: Chemistry:General Chemistry:Properties of Matter,
Resource Type: ActivitiesLab Activity
Special Interest: Quantitative

## Description and Teaching Materials

Materials:
-1 Quart jar
-Tap water
-Blue food coloring dye
-Spoon
-Ice cube tray
-10 ounce clear plastic cup
-Cooking oil

Instructions:
1. Fill quart jar with water and add blue colored dye
2. Pour the blue liquid into ice cube tray and put in freezer; water should freeze in two hours
3. Fill each students' plastic cup 3/4 full of cooking oil
4. Give each student a blue ice cup and tell them to gently place it on top of the oil in the plastic cup
5. Students observe the position of the ice in the oil and draw a picture on paper right after they have placed the ice cup in the oil
6. 5 minutes later, students should draw another picture based on what they see happening

## Teaching Notes and Tips

In this activity, the density of water was shown to be different at different temperatures. Ice floats in oil so it is slightly less dense than oil. Ice and oil will float in water. As the ice cube melted, the denser water sank to the bottom of the cup and collected.

## Assessment

After class has discussed why ice floats on oil and why does water sink below oil, have students answer this scenario:

George is at home and going to fry some chicken in a frying pan. He puts the oil in the pan and turns the stove on. He walks away to watch some TV. He comes back 10 minutes later and the oil inside the pan is on fire. Why should he not put tap water on the oil fire?

## Standards

6.I.B.1 - Scientific inquiry
6.II.B.2 - Mixtures and pure substances