Cells Alive

Time:30-50 minutes

Materials (per pair):

½ cup prepared red gelatin / Freezer-strength sealable, sandwich sized bag / 5-8 grains of white rice / Paper towels
Colored pencils or crayons / 2 sheets of paper / Large spoon

Getting Started

Ask the following true/false questions and have students vote on the answer. Count the votes and write the totals down on the board. Give them the right answer.

  • The heart has two chambers (A: False, the heart has 4 chambers)
  • The upper chambers of the heart are called the atriums and only receive blood from outside the heart. (A: True)
  • Red blood cells are very flexible, so they can pass through very small capillaries to bring oxygen wherever it is needed. (A: True)
  • White blood cells are a water and salt substance that composes 55% of the blood. (A: False, plasma is a water and salt substance that composes 55% of the blood. White blood cells fight off infections and diseases and compose 1% of the blood.)

Directions

  1. Tell the students they will be making a proportional model of blood from gelatin, a plastic bag, and rice. They will use their model to learn about the components of blood and investigate what happens when arteries and veins experience buildup from cholesterol.
  2. Divide the class into teams of two students.
  3. Hand out necessary supplies to each group. The gelatin should be scooped into the bags and sealed before handing it out. Have groups share colored pencils if possible.
  4. Remind students not to handle their gelatin or other supplies just yet.

Part 1: Model of a blood cell

  1. First, ask the students where their heart is located. Give them a moment to point to their chests (or other locations if they are unsure). Then, have them point to the center of their chests and then move their fingers over about an inch or two to their left. This is where their heart is located in the chest cavity.
  2. Next, have one student from each pair very carefully open the gelatin bag. The other partner should place about 6 grains of rice in their bag. Tell the students to reseal the bag very carefully. Make sure it’s fully sealed!!!
  3. Start by grouping the rice together in one corner of the bag.Have students carefully squeeze the bag to move the rice around. Discuss what it feels like, how it looks. Write student responses on the board.
  4. Ask the students the following questions:
  5. Why are there only a few white blood cells? (Answer: The rice represents the white blood cells, and as we learned, there are very few white blood cells in our blood ─ only about 1%.)
  6. Why is it so squishy? (Answer: The red blood cells, water and plasma are represented by the gelatin. The red blood cells, in particular, have to be very flexible in order to travel through tiny arteries, called capillaries.)
  7. Draw the circle diagram on the board and have students draw it on their papers. Tell them it represents the makeup of blood. Write the four components of blood on the board and ask them which label goes where. Let them discuss before giving them the answers!

Water – 50%

Red blood cells – 44%

Plasma – 5%

White blood cells – 1%

Have students color their model accordingly.

  1. (optional)Have the students write a descriptive paragraph about their blood cell.
  2. Next, have five groups (10 students) stand in the front of the classroom. Instruct 2 students to pretend they are blood, and the rest to pretend they are cholesterol (blockage). The students that are the cholesterol line up in twos (standing one foot apart from one another). Now have the blood pass between them. Have the cholesterol students stand right next to each other. The blood will not be able to pass anymore (or at least not easily, if at all). This is what happens when a heart attack occurs. Explain to the students that engineers design medical equipment that helps doctors remove these cholesterol clogs.
  3. Lastly, students will design a way to clean out blocked arteries. Ask them what kinds of heart problems people can have, who fixes them, and why engineers would study the heart. Encourage teams to name their engineering company. Ask them to come up with a way to clean out blocked arteries and encourage them to be creative with their designs: there is no wrong answer. Have students draw a picture of their design and present it to another team or the entire class.