1. Training duration: add up the duration of each training activity. Five training activities were conducted, lasting 2 hours, 3 hours, 1 hour, 4 hours and 2 hours respectively, so the monthly training volume will be 2+3+ 1+4+2= 12 hours.

2. Training class hours: calculated according to the class hours of training activities. Every training activity has a fixed class time. Three training activities have been carried out, which are 2 class hours, 3 class hours and 4 class hours respectively, so the monthly training volume will be 2+3+4=9 class hours.

3. Training times: count the number of training activities. This method is suitable for training activities with relatively fixed duration or class hours. There are eight training activities in a month, so the amount of training in a month is eight. When calculating the monthly training volume, you should include all relevant training activities, and choose the appropriate calculation method according to your specific needs and definitions.