guò / qù / de / lǎo / shī / shàng / kè / shí / cháng / cháng / shǒu / chí / jiào / biān / zhǐ / zhe / hēi / bǎn / jiǎng / jiě

过去的老师上课时常常手持教鞭，指着黑板讲解。

In the past, teachers often held a pointer and used it to explain things at the blackboard.