Awesome Testing

Lesson 04 · Two jobs per block

What changes a token state inside one transformer block?

Unfinished prompt

The animal did not cross the street because it was too

01 · Smallest useful mechanism

Read context, transform locally, keep what helps

A model passes every token state through a stack of transformer blocks. Each block has two complementary jobs. Attention lets a position gather relevant information from other permitted positions. The MLP then transforms the information available at each position independently. Residual connections add each result to a shared working state instead of replacing it, so useful information can persist while new evidence accumulates. Normalization keeps repeated updates manageable. One block usually makes only a partial refinement; depth lets many refinements compose. Think of the stack as a team repeatedly annotating the same working document, not an assembly line where each layer owns one tidy linguistic rule.

Attention communicates between positions; the MLP transforms each position.

02 · Experiment

Test the prediction

Calculate by hand · tiny transformer block

Every displayed update is internally consistent teaching data, chosen so the residual and MLP operations remain inspectable.

One position · one block

Toggle each learned update.

Input R

[0.79, 0.03]

Communicate

+ [0.18, 0.31]

Compute locally

+ [-0.07, 0.22]

Output R next

[0.90, 0.56]

03 · Production-minded practice

Trace one block without hand-waving

Commit to a written claim and evidence plan. The Lab stores the draft locally and never sends it to a server.

Your learning artifact

Write the argument you would defend

Stored only in this browser. No account required; course reset does not delete it.

04 · Check your understanding

Which sublayer directly mixes information between token positions?

Optional referenceDeep dive / reference chapterOpen the complete essay, diagrams, mathematics, exercises, glossary, and sources when you want more depth.

Next: Now isolate the communication job and calculate exactly where one position reads from.