Key Concepts

A submerged object displaces a volume that liquid same to the volume that the object.One milliliter (1 mL) the water has actually a volume the 1 cubic centimeter (1cm3).Different atoms have various sizes and also masses.Atoms on the regular table space arranged in order according to the variety of protons in the nucleus.Even though an atom might be smaller sized than one more atom, it can have more mass.The fixed of atoms, their size, and how they are arranged determine the density of a substance.Density equates to the fixed of the object separated by its volume; D = m/v.Objects through the same mass however different volume have various densities.

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Students usage the water displacement an approach to find the volume of different rods the all have the same mass. They calculate the thickness of every rod, and also use the characteristic density of each product to determine all 5 rods. Climate students take into consideration the relationship between the mass, size, and arrangement of atom to explain why various rods have different densities. Students will certainly be briefly presented to the routine table.


Students will be able to explain the materials have characteristic densities because of the various mass, size, and arrangement of your atoms. Student will have the ability to use the volume displacement an approach to find the volume of one object.


Download the student task sheet, and distribute one per student as soon as specified in the activity. The activity sheet will certainly serve as the “Evaluate” ingredient of each 5-E class plan.


Make sure you and also your student wear correctly fitting goggles.

Materials for Each Group

Set the 5 various rods that all have actually the exact same massGraduated cylinder, 100 mLWater in a cupCalculator

Notes about the materials:

For this lesson friend will require a set of 5 solid rods, each v the very same mass, same diameter, however a different volume. Each rod is made of a various material. There are number of versions of these rods obtainable from different suppliers. This activity uses the same Mass Kit from Flinn scientific (Product #AP4636) yet can be adjusted to any set of equal mass rods. Due to the fact that there are only five samples in the equal Mass kit, you might need two kits so the each group can work-related with a sample.

This graph will assist you recognize each rod. Carry out not reveal this details to the students. Castle will discover the identity of each rod and also the station relationship between the density and also the length of each rod later in this lesson.

Table 1. Physical properties because that solid cylinder unkowns.SampleMaterialApproximate density (g/cm3)Relative lengthSmallest metalShiny gray metalDark grayTall off-whiteTallest white


Show students 5 rods that have actually the exact same mass yet different volumes.

Show college student the five rods and explain the they all have actually the exact same mass. Then hold up the longest, middle-sized, and shortest rods and also remind students that they have the exact same mass.

Ask students to do a prediction:

Which rod is the most dense? least dense? In between?

Students may reason that due to the fact that the mass of each rod is the same, the volume of each rod must have something to execute with the density. Some might go for this reason far as to say the the rod v the the smallest volume must have actually the highest density, since the very same mass is packed right into the the smallest volume. Or the the rod through the largest volume must have actually the shortest density, since the very same mass is spread out over the biggest volume.

Tell students that prefer the cubes in the vault activity, castle will require to know the volume and mass of each of the samples. Lock will also calculate the thickness of each sample and also use this worth to number out which material each rod is make of.

Show one animation and demonstrate how to measure volume using the water displacement method.

Project the computer animation Water Displacement.

Play the computer animation as you show the water displacement an approach using a cup that water, a i graduated cylinder, and also a rod, the method students will perform in the activity. Use the dark gray plastic sample so that students deserve to see the better.


Demonstrate what college student will do by putting water indigenous a cup right into a 100-mL graduated cylinder until it will a height that will cover the sample. This is the “initial water level.”

Tell students that the surface of water in a tube may not be fully flat. Instead, the surface may curve in a shallow U-shape referred to as the meniscus. As soon as measuring, read the line simply at the bottom the the meniscus.


Tilt the i graduated cylinder and slowly slide the sample into the water. Organize the i graduated cylinder upright. Document the level the the water. Point out the this is the “final water level.”

Tell students the you want to uncover out just how much the water level changed. Subtract the initial water level from the final water level to uncover the volume the the rod.

Volume the sample = final water level − initial water level.


Have students calculate the density of five various rods and use the characteristic building of thickness to correctly determine them.

Note: The densities for the three plastics space similar, for this reason students should be an extremely careful when measuring their volume utilizing the water displacement method. Also, that is complicated to measure up the volume that the smallest rod. Give students a hint the it is in between 1.5 and also 2.0 mL.

Question to investigate

Can you use density to identify all 5 rods?

Materials because that each group

Set of five various rods the all have actually the same massGraduated cylinder, 100 mLWater in a cupCalculator

Teacher preparation

Use a permanent marker to note the 5 rods through letters A, B, C, D, and E. Save track of i beg your pardon letter synchronizes to i beg your pardon sample there is no letting students know. If you are using two or much more sets that rods, be sure to note each sample of the same material with the same letter. ~ a group finds the volume that a sample, they should then pass that sample to another group till all groups have uncovered the volume that all five rods. For the longest sample, i m sorry floats, students have the right to use a pencil to gently press the sample simply beneath the surface ar of the water to measure up its complete volume.


VolumePour enough water from her cup into the i graduated cylinder to with a elevation that will cover the sample. Read and record the volume. Contempt tilt the graduated cylinder and carefully ar the sample into the water. Ar the i graduated cylinder upright top top the table and look in ~ the level the the water. If the sample floats, usage a pencil come gently press the optimal of the sample simply under the surface of the water. Record the number of milliliters because that this final water level.

Find the quantity of water displaced by subtracting the early level the the water indigenous the final level. This volume equates to the volume the the cylinder in cm3.

Record this volume in the chart on the activity sheet.Remove the sample by putting the water back into her cup and taking the sample out of your graduated cylinder.DensityCalculate the density using the formula D = m/v. Record the density in (g/cm3).Trade samples through other teams until you have measured the volume and calculated the thickness of all 5 samples. Table 2. Volume, mass, and also density for unknowns A–HSampleInitial water level (mL)Final water level (mL)Volume the the rods (cm3)Mass (g)Density (g/cm3)ABCDE
Identify the samplesCompare the values for density you calculated to the values in the chart. Then create the letter name for each sample in the chart.

Note: The densities students calculate might not be exactly the exact same as the provided densities in the chart. As students space working, examine their worths for volume come be sure that they space using the difference in between the final and initial water levels, not simply the final level.

Table 3. Volume, mass, and also density because that unknowns A–HMaterialApproximate thickness (g/cm3)Sample (Letters A–E)BrassAluminumPVCNylonPolyethylene

Discuss even if it is students’ worths for thickness support your predictions indigenous the start of the lesson.

Discuss student worths for thickness for every of the samples. Suggest out that different groups might have different values for density, however that most of the values room close come the values in the chart.

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Ask students:

Each team measured the volume that the exact same samples. What are some reasons that groups might have different values because that density?Students should realize that little inaccuracies in measure volume deserve to account for differences in thickness values. An additional reason is the the i graduated cylinder, itself, is no perfect. So there is always some hesitation in measuring.

Remind students that in the start of the class they do a prediction about the thickness of the small, medium, and long sample. College student should have predicted the the longest cylinder has the lowest density, the shortest cylinder has the greatest density, and also the center is what in between.

Ask students:

Was your prediction around the density of these three samples correct? have actually students look at at your chart through the values for mass, volume, and density for each cylinder. Have actually them look because that a relationship in between the volume and also the density. Students must realize the the shortest cylinder has actually the best density and the longest cylinder has actually the lowest density. Is it same to say the if 2 samples have the very same mass that the one v the larger volume will have a reduced density? Yes.Why?Because the samples have the same mass, their volumes will give you an idea around their densities follow to the equation D = m/v. If a bigger number for volume is in the denominator, the density will be lower. Is it fair to say that the one v the smaller volume will have a higher density? Yes.Why?If a smaller sized number for volume is in the denominator, the thickness will be higher.