forge.

BOUNDARY BRIDGE

Punctuation is a load-bearing joint. Install the right one, or the bridge will show you why not.
SPAN 1/10 SCORE 0 STREAK ×1 BEST 0
Flint here — and that's my cart on the track. Two clauses, one gap: look at what's standing on each side (a full clause bears weight, a fragment doesn't), then install the joint that'll hold my cart. Pick wrong and, well… you'll see.
?
Flint riding the cart
🚩
SPLASH!
CHOOSE THE JOINT
WORK ORDER #1 — JOIN THE SPANS

A free SAT punctuation game

Boundary Bridge is a browser game about punctuation between clauses, a core Standard English Conventions skill on the Digital SAT. Each round is a sentence split across a gap, and you install the punctuation that legally joins the two sides. Flint's cart crosses when the joint holds. Choose a comma splice or a run-on and the span sags or drops into the gorge, and the game explains what went wrong.

How to play

Read the sentence and decide whether each side of the gap could stand alone as a sentence. Two complete clauses usually take a semicolon, a period, or a comma plus a coordinating conjunction like 'and' or 'but'. When one side is a fragment, a list, or an aside, the joint is often a comma, a colon, a dash pair, or no punctuation at all. Click a joint to install it: if it holds, Flint's cart crosses; if it fails, pick again from the options that are left. First-try installs score the most.

Common questions

Is Boundary Bridge free?

Yes. It runs in your browser with no login and no signup, and it saves your best score locally on your device. The Forge diagnostic it links to is free as well.

What SAT skill does it train?

Punctuation and sentence boundaries, the Standard English Conventions questions that ask where a comma, semicolon, colon, period, or dash belongs between clauses. Each round shows a sentence with a gap and four options for the joint. Only one is legal, and the way to find it is to check whether each side is a complete clause or a fragment before you choose.

What happens if I choose the wrong punctuation?

The bridge fails in a way that matches the mistake, and Flint explains it: a comma splice makes the span sag, a run-on drops the cart in the gap, a semicolon with a fragment tips the beam. You pick again from the options that are left, so a miss becomes an explanation. First-try installs are worth the most points.

Not sure this is where your points are going? The free Forge diagnostic will tell you. More on SAT punctuation rules.

Take the free diagnostic →

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