Letters disappearing as you type? It's probably the Insert key
It usually happens in the middle of homework. Your child clicks into a sentence to fix a word, starts typing, and the letters to the right start vanishing, one for each new letter. Nothing is broken. A key called Insert got bumped, and the computer switched into "type-over" mode.
What's happening
Normally, when you type in the middle of a sentence, the new letters squeeze in and push the rest of the line to the right. That's called insert mode.
When the Insert key is pressed, many Windows programs switch to overtype mode (also called type-over). Now each new letter replaces the letter to its right instead of pushing it along.
| Mode | You type "big" before "dog" in "the dog" | Result |
|---|---|---|
| Insert (normal) | The new letters squeeze in | the bigdog |
| Overtype | The new letters type over the old ones | the big |
How to fix it
- Press the Insert key once. That switches back to normal. On many keyboards it's labeled Insert or Ins and sits above the arrow keys, near Home and Delete.
- No Insert key? Some laptops put it on another key, often combined with fn. Look for "Ins" printed in small letters on a key.
- Check the program. Some word processors let you turn off the Insert key's type-over behavior in their settings, so it can't happen by accident. Look for an "overtype" option.
To get the lost letters back, Ctrl + Z (undo) usually works.
Why it happens so often to kids
The Insert key sits close to Backspace, Delete, and Home on many full-size keyboards. A reaching finger can press it without noticing. Since nothing visible happens when you press it, the first sign is letters disappearing later.
What about Macs?
Macs don't have an Insert key, and most Mac apps have no overtype mode. If letters are disappearing on a Mac, something else is going on, like text that's selected (highlighted) before typing, which replaces the selection.
A quick way to explain it to a child
"The Insert key is a switch. Normally, new letters squeeze in. When the switch is flipped, new letters type over the old ones. Press it once to flip it back."
Then let them try it on purpose in a practice document. Seeing it happen, and fixing it, takes the mystery out of it.
Practice: try it on purpose (Windows)
Open a blank document where overtype is allowed and type:
the dog ran home
- Click just before "dog."
- Press Insert, then type cat. It replaces "dog."
- Press Insert again, click before "ran," and type quickly followed by a space. Now it squeezes in.
Other keys that surprise kids
| Surprise | Usual cause |
|---|---|
| EVERYTHING IN CAPITALS | Caps Lock is on |
| Number pad moves the cursor | Num Lock is off |
| Page reloads and typing is lost | F5 was pressed in a web browser like Chrome. Other apps may use F5 differently |
| Window suddenly fills the screen | F11 was pressed in a web browser like Chrome. Other apps may use F11 differently |
| Text jumps to the start of the line | Home was pressed |
There's more on all of these in keyboard keys explained.
In Home Row Mojo
Home Row Mojo's Keyboard Tour lesson covers Insert as one of the "fixing keys," with the reminder: "If letters start disappearing while you type, Insert is probably on!" The tour has a PC/Mac switch, and on the Mac side it notes that Macs don't have an Insert key. It also covers Caps Lock, Num Lock, the F keys, and the rest of the special keys. Many Chromebooks don't have some of the keys the tour covers, so if that's your setup, try the free version first.
Try Home Row Mojo free as a guest. If it fits, $29 once covers the whole family.