little island 在 / 再: how to tell them apart
在 says where something is or that it is happening now (我在家, 他在看书). 再 means again or next (再见, 明天再来).
在 zài — at, in; to be doing
在
| 现在 | xiàn zài | now / at present | 1A lesson 5 | |
| 正在 | zhèng zài | in the process of | 2A lesson 10 | |
| 记在心里 | jì zài xīn lǐ | to keep in mind | 3A lesson 1 |
再 zài — again; then
再
| 再 | zài | again | 1B lesson 18 |