Will it Sink or Float?

Objectives
TSW demonstrate an understanding of the terms float and sink.
TSW make a list of items they think will sink or float
TSW make predictions about items that will sink or float.
TSW design an object that will float and hold a small Lego man.


(5 minutes) 1. Students and teacher will discuss the two terms float and sink.
(5 minutes) 2. With a partner students will make a list of items they think will sink and a list of items they think will float.
(20 minutes) 3. Divide the class in groups and display items that will sink or float. These items do not need to be bought but collected from home or around the classroom or school. Examples of items could be aluminum foil, variety of fruit, plastic bottles, toy blocks, paper, bathtub toys, plastic spoon, rubber balls, bottle caps, pencils, erasers, sponges, Popsicle sticks, crayons, rubber bands, paper clips, cotton balls, coins, rocks, index cards, or any other small objects. Give each group a simple recording sheet for this activity. The recording sheet will have a list of the items that they will use in the activity. You will need a column for the students' prediction whether the item will sink or swim and a column for the outcome. Each group will also need a small container of water. Divide the items up and circulate them around the groups until each group has been able to see each item. The students should first predict if the item will sink or float. Then they should record the outcome after the put the item in the water. (Having a towel for each group will help keep the mess to a minimum. Also explain to students before they get started that they should not splash or throw the items in the water, but gently put the items in the water.)
(10 minutes) 4. Discuss what floated and what sank. Discuss the properties of the items that floated and sank. Such as what was the item made of and what was the size of the item. Also discuss with students if some of the items changed size or shape would the outcome change. If using aluminum foil roll a piece into a ball and ask if the outcome will change from the previous activity. Also fill the plastic bottle with water and have them predict if it will now sink or float.
(10-15 minutes) 5. Show short video clips of boats and discuss how such big objects made of metal can float. Explain gravity, density, and buoyancy to the students and those three forces work together to help the boats float. If you have a projector you can show the students illustrations of how this works. Great resources for this activity are sciencewithme.com and wonderopolis.org (great video at this website)
(at home project) 6. Students will be given a project to do a home. Students will build an object that will float and can hold a small Lego man. Students may use any type of material, but should make the item their self. Students will bring their "boats" to school at the appointed time and explain how they made it and what materials they used and demonstrated how it can float.