Summary

In this lab students will investigate liquid density by creating model “clouds” with shaving cream in a glass of water. They will add food coloring in order to make the clouds heavy and cause them to rain.

Grade Level

Elementary School

Objectives

By the end of this lab, students should be able to

• Understand that this model simulates real world events in nature.
• Describe, make predictions, and investigate real world meteorological changes.
• Use their senses to identify properties and patterns of objects such as clouds and rain.
• Communicate their observations using related vocabulary and pictures.
• Record and organize data and observations using pictures, numbers, and words.
• Identify and describe weather changes.
• Identify differences in liquid density.

Chemistry Topics

This lab supports students’ understanding of

• Density
• Weather changes
• Water cycle
• States of Matter
• Phase Changes

Time

Teacher Preparation: 15 minutes

Lesson: 60 minutes

Materials (per group)

• Three transparent cups
• 1 can of shaving cream
• 1 box of food coloring
• 1 balance
• 1 pipette
• Running water and access to a sink to pour the experiment after its completion.

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• Do not consume lab solutions, even if they’re otherwise edible products.

Teacher Notes

• As a suggestion, you can pair students during this activity in order to be able to communicate observations.
• This activity could be a good complement after reviewing the units of weather and clouds.
• Review key vocabulary by making an anchor chart since students are required to observe, describe and report the weather using appropriate vocabulary.
• Science background, the following links have additional information.
  • Why clouds stay up?
  • How clouds are formed
• In this unit, we will explore in simple terms the concept of dense materials and density. According to the Merriam-Webster dictionary dense is defined as having parts that are close together. In other words, density is the compactness relationship between the mass of the substance over a volume, and it determines if something will float or sink in another substance. Since density is a complex concept especially for young grades because it has to deal with the displacements of other masses, we will focus on the idea that a denser mass is heavier than a less dense mass of the same size (volume).
• Take a walking fieldtrip outside of the school and describe what the weather and clouds looks like.
• Depending on the grade level, the directions in student section can be read to the students.
• Ask the pre-lab questions as a whole group if you are working with kindergarten and first grade, or let the students do some research in second grade.
• Conclusion: In this activity student will simulate how rain is formed.

1. Since the shaving cream is less dense than the water it is pushed to the top of the cup. Similarly the high density of oxygen gas combined with the temperature helps to push the water vapor into the atmosphere.
2. Since the temperature affects the density of the droplets (vapor) making them less dense and light, the little droplets are pushed to the atmosphere.
3. Once in the atmosphere the little drops start to lose heat making them more dense as they join with other drops forming rain.
4. In our experiment you had to add several drops of food coloring to help make the “cloud” denser and form “rain” inside the cup.