This lesson is based on California's Middle School Integrated Model of NGSS.
MS-PS1: Matter and Its Interactions
PE: MS-PS1-2 - Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. This lesson is specifically designed to assess the property of density within a substance.
DCI: PS1.A: Structure and Properties of Matter - Each pure substance has characteristic physical and chemical properties. Density is a property of matter that can be used to identify it.
SP4: Analyzing and Interpreting Data - Students will make predictions about the possible densities of hot and cold water before the actually build a density column. The students will later analyze their predictions and compare them to actual results.
CCC: Patterns - Macroscopic patterns are related to the nature of microscopic and atomic-level structure. Intrinsic particle movement, often described as temperature, causes water to achieve different levels of density. The students will be able to recognize that these different densities form a predictable patten in nature and can be used to identify specific types of matter.
The purpose of this lab is to give students hands-on experience with density and see for themselves that denser substance will displace less dense substances and sink to the bottom of a graduated cylinder. Buoyancy can be different for objects placed in the same material (water) with varying levels of density (hot vs. cold water).
This lab is often run as part of two other labs:
TIP: The secret to build a clear density column is patience. The drops must be added very slowly and carefully. Any disturbance to the graduated cylinder will result is mixing of the food coloring and will spoil the effect of the density column.
Pass out Liquid Density Lab - Hot and Cold to each student.
Once the students have constructed their density columns they must show their columns to me. I spend a few minutes talking to the group of why their columns were or were not successful.
After I have approved their work they spend a few minutes answering questions before they clean up the equipment.
Student Work Sample