1) To motivate students to experiment, observe, and calculate densities of several different liquids.
2) To show that density is the ratio of the mass of a substance to its volume.
1) Equal quantities of the following liquids:
Liquid A (water)
Liquid B (water plus red food coloring)
Liquid C (water plus blue food coloring)
Liquid D (dark lubricating oil)
Liquid E (light vegetable oil)
2) Transparent plastic cups
3) Graduated cylinders
5) Sets of weights
6) Small paper cups that fit on the pans of the balance
7) Permanent markers
8) Ice cubes (make them green by adding food coloring)
9) Additional quart of vegetable oil
10) Paper toweling
1) Introduce the lesson by telling a story about Mr. Dense and Miss Smile (a teacher). Mr. Dense challenged Miss Smile to have one of her students explain and prove to him why his five unnamed liquids reacted in the manner that he described. The challenge must be met before the end of the week, and the student can't read from a paper. The student must show and explain why mixing equal volumes of A, B, and E, produced different results than mixing equal volumes of A, D, E, and B, D, E, and C, D, E.
2) Place the five bottles of liquids on the table in front of the room as you tell the story.
3) Divide the class into teams based on the number of graduated cylinders available.
4) Each team should use the graduated cylinder to calibrate two transparent plastic cups into 20ml, 40ml, and 60ml by pouring 20ml of water from the graduated cylinder into each cup and marking it with a permanent marker. Repeat for the 40ml and 60ml calibrations.
5) Pour 20ml of liquid A, 20ml of liquid B, and 20ml of liquid C into each calibrated cup.
6) Observe, record, and discuss the results, and pour the contents into another unmarked transparent cup.