Lab goal: build a mini guess game

Success is not “I copied a tutorial.” Success is evidence you can show a friend:

• You chose a threshold (we start at 0.5).
• You turned five scores into five guesses.
• You counted four kinds of outcomes — true hits, false alarms, true clears, and misses — and computed accuracy on this tiny set.

That tiny set is your practice court. Five labeled rounds are enough to check your math. They are not enough to claim the game works for every classmate’s inbox or every gym shot in the world.

Run this exact path. Later pages reuse the same lists so everyone can compare notes.

truth = [1, 0, 1, 1, 0]
scores = [0.8, 0.3, 0.6, 0.9, 0.2]
threshold = 0.5
preds = [int(score >= threshold) for score in scores]

pairs = list(zip(truth, preds))
tp = pairs.count((1, 1)); fp = pairs.count((0, 1))
tn = pairs.count((0, 0)); fn = pairs.count((1, 0))
accuracy = (tp + tn) / len(pairs)
print(preds, f"accuracy={accuracy:.2f}", tp, fp, tn, fn)

Expected evidence:

[1, 0, 1, 1, 0] accuracy=1.00 3 0 2 0

• truth — the real answers for five rounds (1 = yes, 0 = no).
• scores — the model’s confidence each round.
• threshold — the “is it high enough?” cutoff.
• preds — yes/no guesses from score ≥ threshold.
• tp, fp, tn, fn — four scoreboard buckets (correct yes, wrong yes, correct no, wrong no).
• accuracy — fraction of rounds where guess matched truth.

On this fixture the guesses match truth perfectly (accuracy=1.00). Celebrate the math — then write in your notebook: perfect on five practice rounds ≠ ready for every phone.

Fill this sentence: “Given five labeled scores and a threshold, my mini prediction game will print guesses plus TP/FP/TN/FN that match hand counting.” Tape the expected line beside it. If someone later swaps that for “it felt smart,” the sticky note is how you push back.