Ask the students to bring real objects from home such as towels, toothbrushes,
Encourage the stuents to show their items to their friends and discuss them.
You can distribute some papers among the students and encourage them to draw themselves either brushing their teeth, or washing their hands, and so on,.... when they finish you can display the papers on the bulletinboard and keep them there for a week.
Play any song that may be related to this theme and encourage the kids to sing it along with you.
you can also prepare for a play and engage the kids with some roles in order to reinforce the theme.
you can also prepare for a field trip to any available clinic so a doctor can explain more about hygiene.
you can prepare for a healthy cooking session and let the kids help preparing the recipe.
you can prepare for a session to show the kids how to make soap, how to brush their teeth, how to comb their hair and so on,.....