Giving 5th Grade a Hand

This STEM lab rotation find the 5th grade faced with an engineering design challenge. We do a lot of work with the design process in the lab, and even when it is not the focus, it is at the heart of every unit. 

The first part of the process is to understand the task. That includes making observations and gathering information through research. I did not tell the groups what the challenge would be at the start of the unit. However, I did tell them that we would be building several models of mechanisms that move. I also let them know that these activities were meant to provide them with information and ideas they could use for the challenge.

The first make was a two fingered pincher similar to one people use to reach objects on the ground without having to bend over. The two fingers are attached to a piece in the center that the user pulls back bringing the fingers together. Conversely, pushing the center piece forward forces the fingers open. Next, students used card stock paper and brass fasteners to make a scissor mechanism. This is an excellent device for extending the reach of something. Several students had seen the scissor lifts frequently used to reach light fixtures in rooms with high ceilings. Finally, the students made a model of their own hands with independently controlled fingers. Short lengths of straw were attached between each of the joints of the fingers as a stand in for the bones. A string was threaded through each straw and attached to the tip of each finger to mimic the actions of muscles and tendons contracting to pull the fingers closed. Each build was accompanied by a descriptive journal entry of their observations on the device's function and possible uses.

At the start of week two, I introduced the building challenge: design and build a device that can individually pick up a tennis ball, golf ball, cotton ball, and plastic cup and drop it into a bucket. The device must be operated from a distance of at least 24 inches from the objects being picked up. Groups were limited to using a meter stick, cardboard, string, tape, and a few toothpicks or bamboo skewers to make their device work. They started by brainstorming solutions and planning in their journals. Once that was done, they were allowed to start building and testing. Throughout the unit, many groups attempted to make a scaled up version of one of the previous week's models, and some succeeded in doing so. However, the most successful devices were those that adapted the designs in some way. Not every groups was successful, but in the STEM lab that is OK so long as students can articulate why they failed and how they might improve their design given more time. 

I had not done this unit for a couple of years, but I love it because of the variety of designs students create that all complete the same task. It is so important for students to see and to experience that for many questions or problems there are many correct solutions.