SBI4U · What it actually costs
The cheapest way to make an SBI4U lesson
Free, for 3 lessons a month. A full SBI4U lesson plan measured 2,540 output tokens and the free plan includes 10,000, so the first three cost nothing. Past that, Starter at
2,540
tokens per SBI4U lesson plan
Measured in this app on 27 October 2026, not estimated.
3 plans
on the free tier, $0
10,000 tokens a month, reset monthly, no card.
$0.79
per lesson on Starter
$14.95 covers 19 plans a month.
Four ways to a finished SBI4U lesson
Cash is only half the price. Each route below lists what it costs in money, what it costs in tokens, and the catch that makes it cheaper than the next one.
Teach from a free lab
An interactive your students run themselves — membrane transport, enzyme kinetics, or the replication fork, in the browser with nothing to install.
One concept at a time. It carries a lesson, it does not replace the plan around it.
Generate the plan on the free tier
Three full SBI4U lesson plans a month, with Ontario expectations attached and the rest of the free tier behind them.
Monthly allowance, reset included. At the long end of our sample it is three plans; short plans stretch to four.
Starter plan
The free tier’s three plans become 19, so a month that needs five lessons does not stall halfway.
Cheapest paid route per lesson. Worth paying once the free allowance runs out in a real teaching month.
Pro plan
The free tier’s three plans become 39, so a month that needs five lessons does not stall halfway.
Costs more per lesson than Starter. The extra buys chat volume and grading, not lesson plans.
Premium plan
The free tier’s three plans become 98, so a month that needs five lessons does not stall halfway.
A department purchase. One SBI4U section will not clear 98 plans in a year.
Where the 2,540 comes from
We generated three SBI4U lesson plans in this app and logged the output tokens each one produced: 2,172, 2,540, 3,067. We quote the median — 2,540 — because it is the least flattering of the three to quote round numbers from. Nothing on this page is an estimate dressed as a measurement.
Two consequences worth knowing before you buy anything. A long plan can push you to three plans a month rather than four, so treat 3 as a floor on the free tier, not a promise. And we have only measured lesson plans: quizzes, worksheets and rubrics are generated by the same pipeline but their figures are not on this page, because we have not measured them.
The four SBI4U labs that cost nothing
These are already built. They run in a browser, need no account to look at, and spend no generation tokens — which makes them the only route on this page whose price does not move with volume.
Cell membrane lab
Move phospholipids, proteins and water across the bilayer and watch selective permeability hold or fail.
Open the labEnzyme active site lab
Assemble the catalytic triad, bind a substrate, and see why shape decides specificity.
Open the labEnzyme activity lab
Change temperature, pH and substrate concentration, then read the rate curve catalase produces.
Open the labDNA replication lab
Run the replication fork, remove an enzyme, and predict what the new strand looks like.
Open the labSBI4U write-ups that explain how to run each one
- Cell Membrane Lab for SBI4U: the fluid mosaic model in actionBiochemistry · Homeostasis
- Enzyme Active Site Lab for SBI4U: the catalytic triad in actionBiochemistry
- Enzyme Activity Lab for SBI4U: catalase, rate curves and inhibitionMetabolic Processes
- DNA Replication Lab for SBI4U: enzymes of the replication forkMolecular Genetics
- Identifying polysaccharides with Dr. Avery Vance: a Socratic role-playBiochemistry
- Lock and key vs induced fit: an AI role-play on enzyme modelsBiochemistry · Metabolic Processes
Which free resource covers which SBI4U unit
Four units, four labs, and the write-ups that explain how to run each one in class.
Biochemistry
Structures and properties of biochemical compounds, the bilayer, and how enzymes work.
Metabolic Processes
Rate of enzyme-catalysed reactions, and what temperature, pH and inhibitors do to them.
Molecular Genetics
Semiconservative replication, continuous and discontinuous synthesis, one enzyme per job.
Homeostasis
Membrane transport and osmoregulation as feedback the cell actually runs.
When free stops being the cheapest
Three honest cases. Two of them are about money; the third is about whether you would use what you paid for.
You plan more than three or four lessons a month
A working month is often five or six. The free allowance covers three, so the rest is either written by hand or covered by Starter at $0.79 a lesson — less than the cost of the paper you print it on.
Your own time is the expensive part
Nineteen lesson plans written by hand at forty minutes each is about twelve and a half hours. At
You rewrite most of the draft
If the output needs rewriting rather than checking, the cheap route is not the generator — it is the free lab and a discussion. Paying for drafts you discard is the one way this page’s arithmetic breaks.
The plan ladder, per lesson
Free
10,000 tokens · 3 lesson plans a month
$0
first three plans free
Startercheapest paid
50,000 tokens · 19 lesson plans a month
$14.95/mo
$0.79 per lesson
Pro
100,000 tokens · 39 lesson plans a month
$44.95/mo
$1.15 per lesson
Premium
250,000 tokens · 98 lesson plans a month
$99.95/mo
$1.02 per lesson
Pro covers more plans than Starter but costs
Questions about the cost
What is the cheapest way to make an SBI4U lesson?
Free, for three lessons a month. A full SBI4U lesson plan measured 2,540 output tokens and the free plan includes 10,000 a month, so three plans cost nothing. The four SBI4U labs on this site spend no tokens at all, at any volume.
How much does one SBI4U lesson plan actually cost?
At Starter pricing that is
Is the token figure measured or estimated?
Measured. Three real SBI4U lesson plans generated in this app logged 2,172, 2,540 and 3,067 output tokens; we quote the median, 2,540, taken on 27 October 2026. Longer plans use more, which is why the free tier covers three or four rather than a fixed number.
Why does Pro cost more per lesson than Starter?
Do the four labs use up tokens or need a subscription?
No. They are prebuilt interactive pages, so running one spends no generation tokens and needs no plan. They cover one concept each: membrane transport, enzyme active sites, enzyme kinetics, and the replication fork.
What if I teach one SBI4U section and rarely plan from scratch?
Then the honest answer is the free tier plus the labs. Three generated plans a month is more than a single section usually needs, and the labs give you the lessons you would otherwise build activities for.
Start with the part that is free
Run one of the labs this week and generate one lesson plan on the free tier. If you never reach the three-plan ceiling, the cheapest answer is also the one that costs nothing — and there is no card to cancel.