The ce, cet, cette, ces drill
French folds "this", "that", "these" and "those" into a single demonstrative adjective with four written forms. Which form you use has nothing to do with distance and everything to do with the noun: its gender, its number, and its first sound. This page is the hands-on companion to the full demonstratives article - less theory, more repetitions, so the agreement becomes reflex before it can fossilise wrong.
The two-question check
Before every demonstrative, ask two questions of the noun.
Is it plural? Then the answer is , and you are done. Both genders share it: ces hommes, ces femmes, ces enfants, ces choses.
Is it singular? Then the answer is : cette femme, cette maison, cette chose, cette vie.
If neither, the noun is masculine singular and the default is : ce jour, ce temps, ce soir, ce père.
The vowel override
One override sits on top: a masculine singular noun that starts with a vowel or silent h takes , never ce. So cet homme, cet ami, cet enfant, cet an. The reason is pronunciation - French refuses to let the vowel of ce collide with the vowel of homme, so the form grows a bridging t, exactly as le becomes l'.
Two traps hide in the override. First, it only applies to the masculine: a feminine noun starting with a vowel keeps cette (cette heure, never cet heure), because cette already ends in a consonant sound. Second, and are pronounced identically. Speech will never tell you which one to write; only the noun's gender will. If you learned each noun with its article, as the noun gender article insists, the choice costs nothing.
Why drill it
Agreement errors are cheap individually and expensive in bulk: write ce femme a few dozen times and it starts sounding right. The three exercises below run the check in increasing difficulty - the four forms together, then the ce / cet decision on its own, then a mixed set where plurals and vowel-onset feminines are placed to catch you. Every noun comes from the first two hundred words of the course.
When you can clear all three without pausing, the near / far suffixes -ci and -là, and the standalone pronouns celui and celle, are covered in the full demonstratives article.