Teaching design to middle and high school students can be challenging. One of the first procedures in teaching design is to help students gather information that will be useful in the design phase. An early stage of engineering design as described by Lewis (2005), calls for the designer to establish the state of the art of the problem. During this phase, the designer should look for similar problems and study the available solutions. There are many ways designers can increase their references for future use. In this article, the authors use "design reference" as sources of inspiration that increase their understanding of the problem or provide alternate solutions for the problem (Gonçalves, Cardoso, & Badke-Schaub, 2014). Many other disciplines can be used as references for developing a new idea, such as geometric shapes from mathematics, natural structures (such as rocks), and living beings (such as plants and animals). This encourages students to use what they have learned in science, technology, engineering, and mathematics (STEM) disciplines for developing design solutions. Integrated STEM happens when teachers infuse two or more STEM content areas (Sanders, 2009). The STEM lesson described in this article allows students to explore the science of horticulture through inquiry observations and apply this new knowledge in an engineering design task. The engineering design challenge is to create a chair made from cardboard using one or more elements of design (line, shape, texture, color, space, size, and value), drawn from the nature reference. The cardboard chair activity is well known to technology and engineering education teachers and has been adapted for different levels of learners (Linnell, 2007). It can be used as an introductory unit for design activities that involve more complex analysis (for example physical and ergonomics studies performed in the cardboard chair activity). The proposed lesson unit will enable students to "think outside the box" while searching for alternative solutions. It will also stimulate students to reflect on how to use nature references by making them defend the choice in their work. Critical-thinking skills are a desirable trait for learners and are an important component of the technological literacy standards (ITEA/ITEEA, 2000/2002/2007).