The Lab has two ways of entering a trade, and it picks for you based on what the session is trying to teach.
Simple mode — one click
BUY or SELL puts you straight into the trade at a default size. No form, no fields.
Used in: free practice in the Arena, the Daily Challenge, and lesson 1 — Protect every trade with a stop.
The reasoning: the first thing a trader has to learn is where do I get out. Asking someone to size a position before they have internalised the stop is asking them to learn two things at once, badly. So lesson one has exactly one job.
The full ticket
BUY or SELL opens the order ticket, where you set quantity, stop and target and watch exposure and risk update live before you commit.
Used from lesson 2 — Position sizing onwards, because from there the ticket is the thing being taught.
Which am I in?
Look at the hint on the trade bar. In simple mode it reads "press BUY or SELL to enter, then set your stop". With the full ticket it reads "decide size & stop, then place".