Line height is the single most consequential setting on a handwriting worksheet, and it is the one most often guessed. Too big, and letters float in empty space with no size control; too small, and a five-year-old is asked to perform a precision task with a hand that cannot yet tie its own shoelaces. The good news is that line height is not a mystery — it follows motor development closely enough that a millimetre cheat sheet covers most of a class. Here are the numbers, the reasons behind them, and the exceptions.
Line Height by Grade: The Numbers
Line height means the vertical distance from the bottom of one writing line to the bottom of the next — the space a lowercase letter has to live in. The ranges below reflect what actually appears on classroom paper and what hand muscles can realistically control at each age. When in doubt for a whole class, choose the middle of the range and adjust for individuals afterward.
| Age | Grade | Line height | Mode |
|---|---|---|---|
| 5–6 years | Kindergarten | 18–22 mm | Trace large letters, blank row between every line |
| 6–7 years | Grade 1 | 14–16 mm | Trace, then copy on three-line guides |
| 7–8 years | Grade 2 | 11–13 mm | Copy with a visible midline |
| 8–9 years | Grade 3 | 9–11 mm | Narrow-ruled copy, no midline |
| 9 years and up | Grade 4+ | 8–9 mm | Standard exercise-book ruling |
Two practical notes on the table. First, a blank row between traced rows is not wasted paper — it is where the child writes from memory without a model, which is the step that actually builds the skill. Second, the jump from grade 2 to grade 3 (roughly 12 mm to 10 mm) is the steepest of the whole progression; spread it across the year rather than switching paper in September.
The Motor Milestones Behind the Numbers
The millimetre ranges are not arbitrary — they track what the hand can do. Kindergarteners control movement from the shoulder and elbow; the wrist and fingers are still learning their jobs. A 20 mm line fits the size of that whole-arm stroke, and large letters let the child succeed while the small muscles catch up. Through first and second grade, control migrates into the hand itself, and letter size can drop accordingly — roughly one to two millimetres per school year without strain.
Two milestones matter more than age. The first is the tripod grip appearing reliably without reminders; until then, big lines are kinder because a cramped grip has room to relax. The second is the child's ability to stop a stroke on purpose — a controlled start and stop — which is what makes narrow lines fair to attempt. If a student's letters are collapsing into a top line, look at grip and control first, not effort: the line height is usually asking for a milestone the hand has not reached yet.
The Three-Line System, Explained
The classic handwriting guide is three horizontal lines forming two stacked zones: a top line, a dashed or lighter midline, and a baseline. Each letter gets an address. Tall letters like b, d and k touch the top line; short letters like a, e and m sit between midline and baseline; descenders like g, p and y dive below the baseline into the space of the next row. The midline is what makes the system work — it is the ceiling most letters need, and it is why removing it early makes letters swell to fill whatever space is available.
- Baseline: where every letter starts and ends — the one line that must always be visible.
- Midline: the target height for short letters; dashed so it reads as guidance, not a boundary.
- Topline: the ceiling for ascenders; needed until tall letters are consistently tall.
As a rule of thumb, keep all three lines through grade 2. In grade 3, remove the topline first, then the midline once short letters hold their height on their own. Students who lose size control after the guides disappear simply were not ready — return to the guides for another month on new content rather than the same content.
When to Shrink Lines — and When Not To
Shrink line height when a student is consistently filling less than half of the current line with well-formed letters across several sessions — that is the hand telling you it is ready for tighter control. Shrink gradually, one or two millimetres at a time, and keep the midline until short letters hold their height at the new size. The goal of the whole ladder is for letters to look the same at every size, just smaller.
Do not shrink in three situations. First, do not shrink to fit more content on a page: a page with eight well-sized rows beats a crammed page with sixteen miserable ones. Second, do not shrink during a frustration phase — a child whose letters are degrading needs success at the current size, not a smaller target. Third, do not shrink for the whole class because three students are ready: individualize. Many teachers find a mixed approach works — one standard sheet for the class, a shorter-line sheet printed from the same word list for the three ready students, generated in the same session.
A Note for Left-Handed Writers
Line height rules are the same for left-handed writers; what changes is the paper and the view. Left-handers push their hand across freshly written letters, so tilt the paper clockwise (top of the page toward the right shoulder) and seat them where their writing hand is not colliding with a right-handed neighbour. Line height becomes more important, not less: a left-hander whose hand covers the line just written needs a slightly taller line to keep letters legible under the smear of a trailing hand. When in doubt, keep left-handed students on the larger end of the age range one year longer than their right-handed classmates, and prefer worksheets with a blank model row above each writing row so the reference stays visible.
行高是书写练习纸上影响最大的一个设置，却也是最常被"拍脑袋"决定的一个。行高太大，字母飘在空旷的格子里，完全失去大小控制；行高太小，等于要求一个五岁孩子用一双还系不好鞋带的手去完成精密任务。好消息是，行高并不是玄学——它与动作发展贴合得足够紧密，一张毫米速查表就能覆盖大半个班级。下面是数字、数字背后的原因，以及例外情况。
按年级查行高：先看数字
行高，指的是相邻两条书写线的底边之间的垂直距离——也就是小写字母"住"的空间。下面的范围既反映了课堂用纸的实际情况，也对应各年龄段手部肌肉真正能控制的精度。全班使用时拿不准，就选范围的中位数，之后再来个别微调。
| 年龄 | 年级 | 行高 | 模式 |
|---|---|---|---|
| 5–6 岁 | 幼儿园 | 18–22 毫米 | 大字描红，每行之间留空行 |
| 6–7 岁 | 一年级 | 14–16 毫米 | 先描后仿，三线格 |
| 7–8 岁 | 二年级 | 11–13 毫米 | 仿写，保留中线 |
| 8–9 岁 | 三年级 | 9–11 毫米 | 窄行仿写，去掉中线 |
| 9 岁以上 | 四年级及以上 | 8–9 毫米 | 标准练习本行距 |
关于这张表的两点实操说明。第一，描红行之间的空行不是浪费纸——那正是孩子脱开范字、凭记忆书写的位置，真正长本事的步骤就在这一行。第二，二年级到三年级之间（约 12 毫米降到 10 毫米）是整个阶梯中最陡的一跳；请把这一跳摊到一整年里完成，而不是九月一开学就换纸。
数字背后的动作里程碑
毫米范围不是拍出来的，它跟着手的能力走。幼儿园阶段，孩子主要靠肩和肘控制动作；手腕和手指还在"学岗"。20 毫米的行高匹配这种"整条手臂"的笔画尺寸，大字母让孩子先成功，等小肌肉跟上来再说。一到二年级，控制权逐渐交接到手上，字母尺寸随之下降——每个学年缩一到两毫米，完全不会有压力。
有两个里程碑比年龄本身更重要。第一个是三指握姿能在无人提醒下稳定出现；在那之前，大行高更友好，因为局促的握姿需要放松的余地。第二个是孩子能"有意识地收笔"——起笔、停笔都受控——这决定了窄行距对他是否公平。如果学生的字母开始"顶到上横线"，先查握姿和控制，再谈努力：多半是行高在向一个尚未达成的里程碑提要求。
三线格到底怎么用
经典的书写辅助线是三条横线围出的两层空间：顶线、虚线（或浅色）中线、底线。每个字母都有"门牌号"。b、d、k 这样的高个子字母顶到顶线；a、e、m 这样的矮个子字母住在中线和底线之间；g、p、y 这样带尾巴的字母要越过底线、伸进下一行上方的空间。让整套系统成立的是中线——它是大多数字母的天花板，这也是为什么过早去掉中线，字母就会膨胀到填满所有空间。
- 底线：每个字母的起点和终点——永远必须可见的一条线。
- 中线：矮字母的目标高度；画成虚线，读作"参照"而不是"边界"。
- 顶线：上伸字母的天花板；在"高字母稳定地高"之前都需要保留。
经验法则：三年级之前三线全保留。三年级先去掉顶线；等矮字母能自己站稳高度，再去中线。辅助线消失后字母尺寸就失控的学生，只是还没准备好——别用同样的内容补练，换新内容、带线再练一个月。
什么时候缩行高——什么时候不该
当学生在连续几次练习中都稳定地把字母写得只占当前行高的一半以下、且字形完整时，就可以缩了——这是手在告诉你：它准备好接受更紧的控制了。要循序渐进，每次缩一到两毫米，并保留中线，直到矮字母在新尺寸下依然站得住。整架梯子的目标只有一个：任何尺寸下字母都长得一样，只是更小。
三种情况不要缩。第一，不要为了在一页里塞更多内容而缩：八行写得舒展的页面，胜过十六行写得憋屈的页面。第二，不要在挫败期缩——字母正在变糟的孩子需要的是在当前尺寸下的成功，而不是更小的靶子。第三，不要因为三个学生准备好了就全班一起缩：要个别化。很多老师的混合做法很有效——全班一张标准行高，同一份词表再生成一张窄行版，给那三个已经准备好的学生，一次生成、两版都出来。
左利手书写者须知
行高规则对左利手完全一样；变的是纸和视角。左利手写字时手要压过刚写好的笔画，所以把纸顺时针倾斜（页面顶端朝右肩方向），座位安排在写字手不会撞到右手同桌的位置。行高反而变得更重要而不是更不重要：左手会盖住刚写的那一行，稍微加高的行距能让字母在"拖行手掌"扫过之后依然可读。拿不准时，让左利手孩子比同龄右利手多在年龄范围的大一号行高上停留一年，并优先选用"每个书写行上方都留一个空白示范行"的练习纸，保证参照始终可见。