Prior to beginning the lesson, be sure to prepare your "wastewater" which will be treated by students. You will need 200 mL of wastewater for each group. Groups should be 3-6 students. Each group will need a beaker of wastewater and an empty beaker to filter into. 

For Wastewater (in a 2-Liter Bottle):

400 mL vinegar
100 mL lemon juice
1 Tsp salt
1 Tbs sand
lint (collect some from a dryer at home)
hair
food color - don’t use red due to allergic reactions
tap water to fill remainder of bottle

Materials:

funnels (large and small)
top half of a 20 oz. bottle
coffee filters
activated charcoal
ammonia chips
window screen
lima beans
macaroni noodles
cheesecloth
gravel
sand
cotton balls
pH test strips

Links and resources for introduction lessons:

1.Videos to show about need for clean water:
youtube world water day

youtube good: drinking water

Video to show about water filtration process - youtube toilets to tap