Does size change density?

A bigger block has more mass. Does that mean it has a greater density? Use a model to test your idea.

Starting notebook…

Simulation · Mix & Flow of Matter

How does changing the volume of one material affect its mass and density?

Mass tells you how much matter is in a sample. Volume is the space it takes up. Density is mass divided by volume. In this lab, 1 kg/L is the same density as 1 g/mL. Compare samples of the same material before comparing different materials.

Review the related lesson →

Science words you will use

A hypothesis is a possible explanation. A prediction is what you expect to observe. The independent variable is what you change or compare; the dependent variable is what you measure. Controlled variables stay the same in a fair test. Qualitative observations describe what you notice; quantitative observations use numbers and units.

Accuracy means closeness to a trusted value. Precision describes how closely repeated readings agree. Repeating a result does not prove it is accurate. A pattern between two quantities does not, by itself, show that one caused the other.

Your apparatus

Investigate with PhET Density

Use PhET Density. Choose the Intro screen, select one material and change the block size. Read mass in kilograms and volume in litres. Keep the material the same while testing size. Enter your own readings in the notebook. Use the block readings in the control panel, not the total water reading.

Open PhET in a new tab

Choose Intro in the simulation to begin. Record the readings yourself; the notebook does not read the simulation.

PhET Interactive Simulations, University of Colorado Boulder.

Materials & safety

PhET Density simulation
Digital notebook
Calculator, if helpful

This is a computer model. If you later test real objects, keep liquids away from devices and follow your teacher’s instructions.

Suggested procedure — adapt and record changes

Choose the Intro screen in PhET Density. Select one material and keep it the same. Write your hypothesis and prediction.
Set a small block volume. Read the block’s mass and volume in the control panel, including units. Record the material and whether it floats in water.
Repeat for at least three different volumes of that material. Check each reading twice. Repeated readings of a fixed model value are checks, not independent measurements.
Calculate density for every block and compare the results. Plot volume against mass.
Try a second material as a separate set of trials. Keep water conditions the same. Compare materials without mixing up a material change with a size change.

My scientific notebook

Plan your investigation

Use your own words. You can return and change your ideas as you collect evidence.

My research questionWhat can you investigate using this equipment or record?My hypothesisGive a possible explanation: I think… because…My predictionIf… then I predict… because…What I change or compareName the independent variable. In an observation study, name what you compare.What I measureName the dependent variable and its units.What stays the sameWhich material and water conditions will you keep the same when testing size?My procedure and changesUse repeatable steps. Record changes to the plan and why you made them.Reading my equipmentWhat is the smallest marked division? What units and rounding will you use?

Collect · check · compare

Your data and graph

Enter your actual readings. Missing readings stay missing; do not enter zero as a substitute. Keep repeat readings as separate rows. Remove a row only to correct an entry, and record any change in your procedure.

Graph titleGraph view

Think like a scientist

Explain, question and reflect

Patterns in my resultsCompare at least three density calculations for the same material. Is there a pattern? Use pairs of mass and volume values as evidence.Limits and possible errorsHow many digits can you read? A model can give identical results on repeat trials. Why does that not prove real measurements would have no error?My conclusionAnswer your research question. Your result does not have to match your prediction.The evidenceUse measurements, units and trial numbers to support your conclusion.Why the evidence supports my conclusionConnect your observations to the science. Separate what you observed from what you think explains it.What I would improve or test nextWhat would you change? Why? Revisit your hypothesis and prediction.

A new question to explore

Test a different material. Can two blocks with different masses have the same density? Explain using mass and volume.

Keep your work

Your lab report

Download a report with your notes, measurements, calculations and graph. Open it in a browser and choose Print → Save as PDF. Submit that PDF in Google Classroom using your teacher’s instructions. This website does not submit your work.

Restore notebook backup

A backup is a JSON file for restoring this notebook. It is different from your finished report. Keep your own copy before clearing browser data or changing devices.