Hook 5 min

1. Write "line leader = Maya" on the board, then under it "line leader = Leo".
2. "Who is line leader now?" (Leo.) "Where did Maya go?" (Out of the job. It holds one name at a time.)
3. "A computer reads lines like these one at a time, top to bottom. Can you keep up with it?"

Teach 8 min

1. "The orange ▶ shows the line about to run. Line 1 starts with #: a note for people, so the computer skips it."
2. "After line 2, what will apples be?" Everyone holds up a whiteboard guess. A student types the class guess and presses Run line. Fill the board table too.
3. Stop on line 3, apples = apples + 2: "Which side is worked out first?" (The right side: the 3 in apples plus 2 is 5. Then 5 is stored back in apples.)
4. Point to the small grey numbers: every row carries the newest value of each variable.
5. Make one wrong guess on purpose. The guess stays, crossed out, under the real value. "That shows exactly where our thinking split from the computer's."
6. At "Traced!", point to the first-try tally. Show Just show me for a pair that is truly stuck (it counts as not matched).

Practice 17 min

1. Pairs open level 2 from the level dots. Both agree before Run line; switch typists each level.
2. Every pair does levels 2, 4, 6, 7 and 10. Fast pairs do all of them, ending with 12.
3. Level 4, to pairs who missed step 4: "a changed to 9. Why did b stay 4?" (b got a copy of the 4, not a link to a.)
4. Pairs wait at the note card on level 6, The swap. Then stop the class: "Does the note tell the truth?" (No. Both end at 8. The 3 was thrown away when left got the 8.) Pairs tap No, then Next.
5. Repeat levels: "The round rows fill in by themselves. You predict the lines inside."
6. If levels: tap Yes or No, then Run line. "On level 10, why is line 5 skipped?" (75 is not more than 80.)
7. Level 12: "Why does lives stop at 0?" (In round 4: is 0 more than 0? No, so the subtract line is skipped.)

Apply 10 min

1. "Swap the drinks so each cup holds the other color. You can only pour." A student tries with two cups. (They mix, like level 6.) "What would help?" (The empty cup.) Swap using the third cup.
2. On the projector, open Workbench and pick Swap with a spare. Press Step row by row. "Which line pours into the empty cup?" (spare = left.) "Did both values survive?" (Yes: it says 8, then 3.)
3. Pick Doubling tower. Tap the 3 in repeat 3 times and press + once. A yellow ? appears on the note. Step to the end. "Is the note still true?" (No. It doubles 4 times and ends at 16.)
4. Pairs write a new true note on whiteboards. Read two aloud, then press Reset numbers.

Exit check 5 min

Students trace this in a table (Step, Line, score, Says):

```

the score never goes above 10

score = 4 repeat 3 times: score = score + 3 say score ```

"Does the note tell the truth?" (4, 7, 10, 13; it says 13. No.) Note who loses track of rounds.