Exercise 2 solution

Example answer (yours will differ):
First: weed the bed thoroughly, removing perennial roots, and water well so the soil is damp all the way down. Mulch seals in moisture, so it must go on damp soil, not dry.
Material: well-rotted compost (or leaf mould, or well-rotted manure). Straw also works between larger plants.
Depth: about 5 to 7 cm over the whole 2 m2 surface.
When: mid to late spring, once the soil has warmed and plants are established; top up in summer if thin.
Avoid: piling mulch against plant stems (keep a finger-width or more gap, so stems do not rot and slugs have no shelter); using fresh manure, which can burn roots; mulching over weeds that have not been dug out; or spreading it on dry soil.