Discrete distribution of daily rainfall
Put a cylindrical beaker out in the open at mid day. Remove it at mid day on the following day. Measure the depth of the accumulated rainfall and divide by 24 to give the average rainfall per hour, and divide that by 6 to give the average per 10 mins. In the summer, some of your collected rainwater will be lost through evaporation, so to find that, put your beaker of water outside, but under some sort of roof. Measure the depth when you put it out, and measure it next day when you take it in. That will give an idea of losses due to evaporation, which reckoned in losses every ten minutes would by tiny. If there is not much rain but plenty of hot sunlight, things become tricky, because you will be measuring very tiny quantities. Other than that, you could camp outside and weigh your beaker every 10 minutes, but that's not something I would do myself. The roof I mentioned is only necessary if it is raining, because rain would destroy your figures for evaporation.