A metal ball and a wooden ball
D. Hygiene education
The outbreak of influenza caused many hospitals to post articles about how to avoid the flu and they have recommended to minimize the contact with influenza by taking of your hygiene and staying away from family members/friends with the sickness.
It's a fun, and interesting thing to do. It's a great help towards your community and you benefit in the end with people and working skills. It's also great if you need some extra curriculars for your college applications.