Joins are the whole point
Cursive exists so the pen stays on the paper between letters. The connector between two letters is not decoration; it is the exit stroke of the first letter continuing into the entry stroke of the second, and where those two strokes meet depends on which letters they are. Most joins happen at the baseline and take care of themselves. The ones that need teaching are the pairs where the first letter ends somewhere else.
Five kinds of join
Baseline joins are the default: the first letter ends at the baseline and the next starts from there. Bridge joins follow b, o, v and w, which end at the midline, so the next letter has to take a short horizontal entry instead of rising from the baseline; this is why "bo", "ov", "wa" and "or" look different from "ba", "ca" and "ma". Loop joins carry the connector through a looped ascender or descender, as in "fl" or "gr". Drop joins fall from the midline back to the baseline, typical after a letter that ends high into one that starts low. Cross joins use the crossbar of t or f as the connector into the next letter, as in "tt" and "ft".
The pairs learners find hardest
The bridge joins after b, o, v and w lead the list, followed by anything into s (which starts with a small loop the connector must reach), double letters where the second must differ slightly from the first, and any pair with an r, whose shape changes depending on what follows. Each pair page renders the join large, explains what happens and prints example words.
Learning joins in order
Teach baseline joins first, in words made from the oval and upstroke families such as "cat", "man" and "dad". Bring in bridge joins next with "on", "or", "we" and "by", because they change the shape of the letter that follows. Cross joins and loop joins come with t, f, l and g. Double letters come last: "ll", "tt", "oo" and "ss" each need the second letter written slightly differently from the first so the pair reads as two. The pair pages follow this order, and each links to a practice sheet.
Fonts and joins
Not every cursive font joins its letters, and the ones that do use OpenType rules to swap letter shapes depending on their neighbours. The font pages classify every catalogue font as fully joined, semi-joined or unjoined from an automated audit of all 676 pairs, and list the pairs that fail in joined fonts.