After the story, there are many math activities you can do. Here are some ideas taken from the Marilyn Burns lesson on Scholastic.com.
I have also created a Google Form where I have embedded the Chrysanthemum YouTube video. (Here is the link to the Live Google Form.) You can share the form with students or add it as an assignment in Google Classroom so that students can watch the video on their own and then type in their first names and the number of letters in their first names. The data will automatically be placed into a Google Sheet. The data collected in the spreadsheet can be shown in many different ways. You can show students how the spreadsheet can calculate the total number of letters in all of the students' names. You can also insert a chart (insert>chart) and the charts that will work with your data will be displayed. You can choose the one you like, click on it, and it will be inserted right into your sheet. Here is an EXAMPLE I created for this lesson.
Another idea you can use for the data is to have students calculate how much money their names are worth. Here is a Google Doc I created that can be shared with students or added as an assignment in Google Classroom.
And as always, feel free to copy any items I have created and edit and use them however you would like!