I've found a great grammar exercise. Could you check it?
Ex. 26. (A, B). Find the sentences in which: a) “-ing” form is a gerund, b) a verbal noun.
1. You should think before speaking. (speaking - gerund)
2. After finding the new word in the dictionary, I wrote it down and went on reading. (finding – gerund, reading – gerund)
3. He spent much time on the copying of his literature lectures. (the copying – verbal noun)
4. What do you mean by saying that? (saying - gerund)
5. The students found the reading of English newspapers rather difficult at first. (the reading – verbal noun)
6. Instead of going home after school, the girls went for a walk. (going - gerund)
7. Chalk is used for writing on the blackboard. (writing - gerund)
8. We sat by the river-side listening to the running of the water. (running) – verbal noun9. The cleaning of the room was done by the girls. (The cleaning – verbal noun)
10. Working in the garden is very good for the health of people. (Working - gerund)
11. I stopped knocking at the door and began waiting for my father to come. (knocking, waiting - gerunds)
12. She praised herself for having come. (having come - gerund)
13. The child stopped crying and quieted down to hard thinking. (crying – gerund, thinking – verbal noun)
14. The old clock kept ticking on the mantelpiece, as if counting the seconds left before the coming of daylight. (ticking –gerund, the coming
P.S.: I tried really hard to do this exercise correctly. In some cases I have doubts about choosing the correct option.