Students will create a cross section of a femur using cardboard, sponge, paper towel roll, and paper maché. Use Image #1 (page 3) as a reference and template to prepare materials. Depending on background knowledge of the students, and grade level, you may choose to leave out some of the labels from the image such as: articular cartilage, medullary cavity, and ephephyseal plate. The labels essential to this lesson are: periosteum, compact bone, spongy bone, marrow, and blood vessels
Materials:
Image#1 (page 3) drawn or projected onto a white board, or drawn on chart paper.
An actual mammal bone cut in cross section (often available from a supermarket butcher)
Corrugated cardboard - "Recycled" science fair display boards work well
Large sponges (usually used for washing cars) - cut in half at midline
Empty paper towel rolls
Thick red yarn or cord
Newsprint or newspaper cut into strips
Paper maché paste – old fashioned wheat paste works well
Soft, flexible wire mesh to support paper maché (optional)
White or "bone" colored paint
Regular school glue
Scissors
Teacher prep: Cut corrugated cardboard into bone shapes, one per student (refer to Image#1 for shape). Prepare paper maché paste. Cut wire mesh - sized to fit over bone shapes. Have newsprint and other thin papers cut into small strips and set aside in a bin. Make a "prototype" bone to be used as a model for the class lesson
Step One: Introduce lesson by asking students if they know what their bones look like inside. If students are feeling confident about their knowledge and artistic ability, ask for volunteers to draw a diagram on white board or chart paper. Students should write their own predictions and drawings in their own interactive science notebooks.
Step Two: Show students your prototype model of the bone cross section, and the actual bone, if available, or if they are likely to be overwhelmed by too much information at one time, just show the portion of Image#1 that displays the periosteum and compact bone. Then hand out the pre-cut cardboard pieces and wire mesh that form the frame of the bone model. Use the image, the "prototype" and the cardboard bone frames to describe the periosteum layer and the compact bone beneath it. Briefly point out the other bone parts, letting the students know that you will return to them later.
Step Three: Now students are ready to use the paper maché, cardboard frames and wire mesh to create the periosteum. Extra pieces of cardboard can be glued directly under the periosteum layer to serve as compact bone, to be covered with paper maché, (then painted differently later in the project) to show the difference between periosteum layer and compact bone layer. Make another model with the students as to demonstrate each step along the way. Tape the wire mesh onto the cardboard to give it a 3D bone shape. Demonstrate how to apply the strips of paper dipped in paste to the frame. When a thin layer of paper maché has been applied, set models aside to dry. Students should have their names attached to the models. Wrap up this portion of the lesson by having students note vocabulary, make drawings and describe their experiences of the project so far in their interactive notebooks. (The final layers of paper maché will be applied after the interior of the model is complete).
Step Four: This step begins at least one day following Step Three when the first layer of paper is dry. Have Image#1 and prototype bone model displayed. Have cut sponges ready to use in classroom. Begin lesson by pointing out the spongy bone section in the model and the image. Ask some opening questions to start the children thinking about bones and bone structure. "What do you think the spongy bone feels like?" Why isn't it solid like the periosteum or the compact bone? Do you think it is strong or weak? Do you think it is heavy or light? Take a few moments to discuss answers and have students record the newly learned facts into their interactive notebooks. Having an actual mammal bone is helpful at this point because students can see and feel the hardness of the spongy bone. Distribute the cut sponge pieces and direct them to glue the pieces into the bone models to match the image. After gluing have them record any final observations, facts, vocabulary or drawings pertinent to the lesson in their notebooks.
Step Five: This step can be done immediately after the spongy bone activity or it can be presented as a separate lesson on the following day. Begin again with Image#1, the prototype model, and the model in progress. Have paper towel rolls, red yarn, and glue ready for use. Start the discussion with a mini lesson on bone marrow structure and its function. Distribute paper towel rolls and have students glue them into the center of the bone model. Then distribute the red yarn so students can attach blood vessels using Image#1 and the prototype model as a guide.
Step Six: This is the final step in completing the models. It will need to be spread out over a few days to allow for drying of paste and paint. It is also an excellent time to review the bone parts and their functions as children are working. Have paint, paper and maché paste ready to use and more red yarn to add blood vessels in different layers as needed. Over the course of two to four sessions students will add layers of paper maché to the periosteum and compact bone. When all layers of paste are dry, students can paint and label the models to complete the project.(Image #1)
