Best examples of comparative study of biodegradable vs non-biodegradable materials for science fairs

Strong examples of comparative study of biodegradable vs non-biodegradable materials

Let’s start with what you actually need: real, testable project ideas. Here are several examples of comparative study of biodegradable vs non-biodegradable materials that students can realistically run at home or in a school lab.

Example 1: Grocery bag breakdown in soil

One classic example of comparative study of biodegradable vs non-biodegradable materials is to compare how different grocery bags break down when buried in soil.

You might compare:

• Biodegradable grocery bags labeled “compostable” or “plant-based”
• Regular polyethylene plastic grocery bags
• Paper bags

You bury equal-sized pieces of each material in identical containers filled with the same type of soil, kept at similar moisture and temperature. Over several weeks or months, you:

• Weigh the samples at the start and at intervals
• Record visible changes: tearing, color change, fragmentation
• Note any mold or fungal growth on biodegradable samples

This gives you quantitative data (mass loss) and qualitative data (appearance). It also lets you ask a sharp question: Do commercial “biodegradable” bags actually break down faster than standard plastic bags under typical backyard soil conditions?

Example 2: Food containers in a simulated landfill vs compost

Another strong example of comparative study of biodegradable vs non-biodegradable materials focuses on food packaging. Many brands now sell compostable cups, plates, and takeout containers.

You can compare:

• Compostable PLA (polylactic acid) cups or cutlery
• Regular polystyrene foam (Styrofoam) cups
• Paper cups with plastic lining

Set up two environments:

• A “landfill” model: sealed or nearly sealed container with limited oxygen and low moisture
• A “compost” model: aerated container with moist soil or compost and some organic matter (like leaves)

Place identical samples of each material in both environments and track:

• Changes in mass over time
• Structural integrity (do they crack, crumble, stay solid?)
• Any visible biological activity (fungus, insects, etc.)

This example lets you compare not only biodegradable vs non-biodegradable materials, but also how disposal method (landfill vs compost) affects the results. It mirrors real-world debates: a compostable cup in a landfill often behaves a lot like regular plastic.

Example 3: Biodegradable vs plastic straws in water

Plastic straws have become a symbol of ocean pollution. A very visual example of comparative study of biodegradable vs non-biodegradable materials is to immerse different straw types in water.

You can compare:

• Paper straws
• PLA or “plant-based” compostable straws
• Traditional polypropylene plastic straws

Place each type in jars of tap water or saltwater and record:

• Time until visible softening or structural failure
• Changes in color or cloudiness of the water
• Any particles or fragments floating or sinking

You can extend this by gently agitating some jars daily to simulate wave motion. This project connects directly to current research on marine plastic pollution and microplastics. For background on marine debris and plastics, the NOAA Marine Debris Program has useful resources: https://marinedebris.noaa.gov/

Example 4: Soil quality after degradation of different materials

If you want to go beyond “does it disappear” and actually test environmental impact, this is one of the best examples of comparative study of biodegradable vs non-biodegradable materials.

You can bury:

• Biodegradable bag pieces
• Regular plastic bag pieces
• Plain paper pieces

After several weeks or months, you:

• Remove remaining material (if possible)
• Test soil characteristics in each container

Possible measurements (depending on what your school can support):

• pH changes using simple pH strips or a soil pH meter
• Plant growth tests: plant fast-growing seeds (like radish or beans) in each soil and compare germination rate and plant height
• Soil appearance: texture, smell, color

This approach highlights that “biodegradable” is not automatically “environmentally harmless.” Some bioplastics can produce acidic byproducts or affect soil microbes differently than natural materials. For broader context on soil health and organic matter, the USDA NRCS has accessible information: https://www.nrcs.usda.gov/

Example 5: Microplastic formation from biodegradable vs conventional plastics

This example is more advanced, but it’s powerful if you have a microscope.

You compare:

• Conventional plastic film (like a standard grocery bag)
• A certified compostable plastic film (labeled ASTM D6400 or EN 13432)

Cut equal-sized pieces, then:

• Expose them to sunlight (or a UV lamp if available)
• Optionally add abrasion: gently shake with sand or small gravel in jars

Over several weeks, examine water or surface scrapings under a microscope to see if both materials form tiny fragments.

This example of comparative study of biodegradable vs non-biodegradable materials lets you ask: Do biodegradable plastics reduce microplastic formation, or do they just break into smaller pieces faster? That question is very current in 2024–2025 as scientists debate the real-world performance of bioplastics.

Example 6: Decomposition of everyday household items

If you want something that feels directly connected to daily life, you can compare common items:

• Biodegradable: paper towels, cotton cloth, wood toothpicks, cardboard
• Non-biodegradable: plastic utensils, plastic bottle caps, aluminum foil, snack wrappers

You can bury them in soil, submerge them in water, or place them in a compost pile if you have one.

Track:

• Visual changes at regular intervals (weekly photos and notes)
• Mass loss where possible
• Any odor changes (which may indicate active microbial decomposition)

This is one of the best examples of comparative study of biodegradable vs non-biodegradable materials for a middle school project because it’s easy to understand, cheap to set up, and produces dramatic results over time.

How to design a strong comparative study (without making it boring)

Once you’ve picked your favorite example of comparative study of biodegradable vs non-biodegradable materials, the quality of your project depends on design. Judges look for clear variables and real data, not just a pile of moldy paper towels.

Define your variables clearly

For almost all examples of comparative study of biodegradable vs non-biodegradable materials, you can structure the experiment like this:

• Independent variable: The type of material (biodegradable vs non-biodegradable; paper vs plastic; compostable vs conventional)
• Dependent variable: What you measure (mass loss, time to visible breakdown, change in soil pH, plant growth, water clarity, etc.)
• Controlled variables: Temperature, moisture, light exposure, size of samples, amount of soil or water, container size

Write these out before you start. It not only improves your project; it also makes your display board and explanation much sharper.

Choose realistic time frames

Here’s the hard truth: some non-biodegradable materials barely change over a school year. That’s actually good data.

For many examples of comparative study of biodegradable vs non-biodegradable materials, you’ll see:

• Paper and food waste change noticeably in 2–4 weeks
• Some bioplastics show early changes (softening, cracking) in 4–8 weeks
• Conventional plastics may show almost no visible change in months

If your project timeline is short, pick materials that are known to break down faster (paper, cardboard, natural fibers) so you can show a clear contrast.

Collect both quantitative and qualitative data

Judges love numbers, but photos and descriptions matter too.

For each example of comparative study of biodegradable vs non-biodegradable materials, try to include:

• Starting mass of each sample and mass at each time point
• Number of days until a certain change (for example, “first visible tear” or “completely disintegrated”)
• Photos at consistent intervals from the same angle and lighting
• Written observations: color change, odor, mold growth, fragmentation

This combination makes your project feel like real science, not just a craft project that got left in the backyard.

Connect your project to current data and trends (2024–2025)

To elevate your project beyond the basics, link your results to current research and policy.

A few 2024–2025 trends you can mention:

• Many U.S. cities and states are restricting single-use plastics and encouraging compostable alternatives.
• Studies have shown that some “biodegradable” plastics only break down quickly in industrial composting facilities, not in home compost or landfills.
• Microplastics have been found in drinking water, soil, and even human blood and lungs. The World Health Organization and U.S. agencies are tracking this closely. For general information on environmental health and plastics, the EPA is a good starting point: https://www.epa.gov/trash-free-waters

If you want to go deeper, you can look at research from universities (for example, search “biodegradable plastics environmental impact site:.edu”). Many .edu pages summarize current science in student-friendly language.

Turning your project into a strong science fair presentation

You can have the best examples of comparative study of biodegradable vs non-biodegradable materials, but if your presentation is unclear, judges may miss how good your work is.

Organize your display board around the comparison

Instead of a generic layout, lean into the comparison theme:

• One side focused on biodegradable materials
• The other side focused on non-biodegradable materials
• A center section for graphs, tables, and your main conclusion

Include:

• A short, sharp research question: for example, “Which breaks down faster in backyard soil: compostable bags, paper bags, or regular plastic bags?”
• A hypothesis that compares groups: “If biodegradable and non-biodegradable bags are buried in soil, then paper and compostable bags will lose more mass than conventional plastic bags over six weeks.”
• Graphs that show the contrast clearly (bar graphs or line graphs work well)

Anticipate judge questions

For any example of comparative study of biodegradable vs non-biodegradable materials, judges might ask:

• “How do you know your material is really biodegradable?”
• “Could the conditions in your experiment be different from real landfills or oceans?”
• “If something breaks into tiny pieces, does that automatically mean it’s better for the environment?”

Prepare short, honest answers. It’s fine to say, “My experiment can’t fully copy a real landfill, but it helps show how different materials behave under the same controlled conditions.” That kind of answer shows scientific thinking.

FAQs about examples of comparative study of biodegradable vs non-biodegradable materials

Q1: What are some easy examples of comparative study of biodegradable vs non-biodegradable materials for middle school?

Good starter projects include comparing paper vs plastic bags in soil, paper vs plastic straws in water, or cotton vs polyester fabric buried in soil. These materials are cheap, safe, and show visible differences in a few weeks.

Q2: What is one advanced example of comparative study of biodegradable vs non-biodegradable materials for high school?

A strong advanced example is tracking microplastic formation from a compostable plastic film versus a conventional plastic film using a microscope. Another is measuring soil pH and plant growth after different materials decompose in the soil. These projects generate deeper data and connect directly to current environmental research.

Q3: How can I make sure I’m not just doing a “watch it rot” project?

Focus your example of comparative study of biodegradable vs non-biodegradable materials on measurable outcomes: mass loss, time to disintegration, plant growth, pH change, or water clarity. Set up controls, keep conditions consistent, and collect data on a schedule. That moves your project from “I buried stuff” to “I ran a controlled experiment.”

Q4: Do biodegradable plastics always disappear completely?

No. Many “biodegradable” or “compostable” plastics are designed to break down under specific industrial composting conditions (high temperature, controlled moisture, active aeration). In regular soil, backyard compost, or landfills, they may break down slowly or fragment into smaller pieces. That’s why a good comparative study is valuable: it tests real-world behavior instead of just trusting the label.

Q5: Where can I find reliable background information for my project?

For general information on waste, plastics, and environmental health, the U.S. Environmental Protection Agency is a solid source: https://www.epa.gov/. For soil and composting basics, the USDA NRCS site is helpful: https://www.nrcs.usda.gov/. You can also search university (.edu) websites for “biodegradable plastics,” “microplastics,” or “compostable packaging” to find summaries of current research.

If you build your project around one of these examples of comparative study of biodegradable vs non-biodegradable materials, keep your variables clear, and collect real data over time, you’ll end up with a science fair project that’s not only environmentally relevant, but also scientifically impressive.