Recall without looking
When is a feature available? Which data choose hyperparameters? Why compare a baseline?
Check and explain
Prediction-time availability prevents leakage. Use training/validation or cross-validation for selection and reserve an untouched test. A simple baseline establishes whether complexity adds useful evidence.
Transfer task
Sketch a churn prediction timeline, flag closure-derived features and define an evaluation metric aligned with errors. This exercise does not train a model.
Record your next review
Write which concept you missed and one new example. Revisit after 2–3 days, then about a week; adjust the interval to your needs. This is a suggested study routine, not an automated reminder or saved score.
Try the activity before reading its reference. Keep your sources, commands and assumptions with your work. Companion activities are unsaved self-practice and do not award a certificate or change lesson progress.