% Mass remaining
Data, graphing & stats
Plot % mass remaining vs. week for each material (line chart).
Compare slopes or Week-8 values between materials.
If you’ve got 3+ replicates, you can add error bars (±1 SD). A simple t-test on
Week-8 % remaining between LDPE vs. PLA can support claims (optional at
school level).
Controls & quality checks
Negative control: LDPE (should show little to no mass loss).
Positive control: Orange peel (should lose mass quickly).
Keep all non-material factors identical.
Always dry to the same endpoint before weighing (moisture is the #1
confounder).
Safety & ethics
Wear gloves; wash hands after handling soil.
No pathogenic organisms or sharp items.
Get adult supervision for any oven work.
Common pitfalls & fixes
Samples gain weight week-to-week: Not fully dried → extend drying, cool in
a closed container, then weigh.
PLA shows little change: Many “compostable” plastics need higher
heat/industrial composting. That’s still a valid result—discuss conditions.
Mold explosion: It’s okay—note it; it often speeds decomposition for
organics.
Extensions (bonus points)
Compare soil vs. compost conditions.
Test thicker vs. thinner samples.
Add a microbe-reduced control (soil microwaved and cooled) to show
microbial role.
Photograph samples weekly and analyze % area damaged using a grid
overlay.
I also made you a ready-to-use data sheet (CSV) with columns for week-by-week
measurements and three replicates per material. You can open it in Excel/Sheets:
Download the Decomposition Data Sheet Template
If you want, I can also generate a clean graph template you can drop your numbers
into.
You said:
rewrite the project in other form
ChatGPT said:
Here’s your project rewritten in a clean, concise “school science fair” style that’s
easier to present and submit.
Title
Comparing the Decomposition Rates of Biodegradable and Non-Biodegradable
Materials in Soil
Aim
To investigate how quickly biodegradable materials break down in soil compared to
conventional plastics under the same environmental conditions.
Research Question
Which type of material—biodegradable or conventional plastic—loses mass faster
when buried in soil for several weeks?
Hypothesis
Biodegradable items such as paper and compostable plastics will lose mass
significantly faster than non-biodegradable plastic when buried in soil.
Variables
Independent Variable: Type of material (LDPE plastic, compostable PLA
plastic, uncoated paper, orange peel).
Dependent Variable: Percentage of original dry mass remaining over time.
Controlled Variables: Soil type and quantity, moisture level, temperature,
burial depth, sample size,
