A quick estimation game: see an everyday item · a banana peel, a tin can, a plastic bottle · and pick how long it takes to break down in nature. One wrong answer ends the streak, and your best score is saved locally in your browser.

Where do the decomposition times come from?

From the widely-cited environmental-education tables, principally NOAA marine-debris material. Real decomposition depends on moisture, temperature and burial, so the game uses coarse, defensible magnitudes · the skill being trained is magnitude sense, not memorising lab data.

Can I study just one category?

Yes. The picker on the start screen filters the pool to nature & food items, human-made materials, or everything. Each category keeps its own best streak.

How does it get harder?

Two ways: as your streak grows the wrong answers move closer to the true duration (450 vs 600 years instead of 1 month vs 1 million years), and an extra answer option joins the row.

Can I print it as a worksheet?

Yes. Decay Time supports the printable worksheet generator at /worksheets · each problem prints with lettered duration choices and an answer key, a ready-made handout for environment and recycling units.

Can MemPi help me study and practice this game?

Yes! Click MemPi in the header or on the game board to summon him. He observes the board, thinks out loud, and can demonstrate moves or guide you through tricky steps.

Decay Time

How long until it is gone? Guess how long everyday things take to decompose · from banana peels to glass bottles

About Decay Time

Decay Time is a quick estimation game about how long everyday things take to break down in nature. A banana peel? About a month. A plastic bottle? Around 450 years. A glass bottle? Closer to a million. Each round shows one item and a handful of durations · pick the closest one and keep your streak alive.

Real numbers, coarse on purpose. The durations come from the widely-cited decomposition tables used in environmental education (NOAA's marine-debris material and the posters derived from it). Exact times depend on conditions, so the game tests magnitude sense · weeks vs decades vs centuries · not lab precision.

Choose what to study. Play the full mix, or filter to nature & food (peels, paper, cotton, wool) or human-made materials (plastics, metals, glass). The distractor durations close in as your streak grows, so long runs demand genuinely sharper estimates.

Part of the PlayMemorize family of brain-training games.

How to master

New game videos on YouTube

YouTube channel

FAQ

What is Decay Time?

A quick estimation game: see an everyday item · a banana peel, a tin can, a plastic bottle · and pick how long it takes to break down in nature. One wrong answer ends the streak, and your best score is saved locally in your browser.
Where do the decomposition times come from?

From the widely-cited environmental-education tables, principally NOAA marine-debris material. Real decomposition depends on moisture, temperature and burial, so the game uses coarse, defensible magnitudes · the skill being trained is magnitude sense, not memorising lab data.
Can I study just one category?

Yes. The picker on the start screen filters the pool to nature & food items, human-made materials, or everything. Each category keeps its own best streak.
How does it get harder?

Two ways: as your streak grows the wrong answers move closer to the true duration (450 vs 600 years instead of 1 month vs 1 million years), and an extra answer option joins the row.
Can I print it as a worksheet?

Yes. Decay Time supports the printable worksheet generator at /worksheets · each problem prints with lettered duration choices and an answer key, a ready-made handout for environment and recycling units.
Can MemPi help me study and practice this game?

Yes! Click MemPi in the header or on the game board to summon him. He observes the board, thinks out loud, and can demonstrate moves or guide you through tricky steps.