Exercise 1 solution

Example answer (yours will differ), for courgettes:
Days 1-3: 2-3 hours outdoors in a sheltered, shaded spot; in at night.
Days 4-6: 4-6 hours with morning sun; still in at night.
Days 7-9: all day in the open; leave out overnight only if no frost is forecast.
Day 10: plant out in the bed on a cloudy day or in the evening, and water in.
Frost forecast on day 8: keep the tray indoors that night (a cool porch or windowsill), or cover outdoors with fleece. Resume next day. Do not plant until the frost risk has passed; the hardening-off period can simply be extended by a few days.