Summary
An engineering-focused STEM curriculum should observe five basic principles:
The curriculum theme should be connected to real-world situations.
The scope of the stem subject knowledge should be defined meticulously to outline the curriculum content clearly.
The overall curriculum planning should be conducted based on the engineering design process, with a focus on stages that include problem definition, solution development, analysis, modeling, testing and modification, and optimization (6 steps for Engineering-Focused Curriculum).
Systematic, practical “inquiry and experiment” and “design and making” learning activities should be conducted to highlight the connections between the curriculum theme and stem subject knowledge and aid in construction of the required knowledge, experiences, and skills.
The teaching strategies should offer a cycle of learning experiences and emphasize the exploring, interpreting, practicing, modeling, testing, connecting, and applying of knowledge.

Relevance for Complex Systems Knowledge
The STEM curriculum should possess: (1) Real world background, (2) Integration STEM content, (3) Inquiry and project/problem based learning, (4) Active learning and (5) High level thinking skills.

The integration of content from different disciplines makes it possible to develop knowledge and skills that are not limited to a single subject. Thus, there are two models of integration:
a) Focused on subject-specific content: the axis is formed by a single discipline (or two) and the rest complement the knowledge. As a consequence, students only develop deep content and skill knowledge for the main discipline
b) PBL context: Involves moving beyond the traditional framework of each discipline and adopting a project-oriented curriculum structure to re-integrate and re-organize related STEM subject knowledge according to the chosen theme.

This paper defines Engineering as the main axis for STEM projects so, it has to be taken into account that Engineering consist of “design under constraints” which is a problem solving process for satisfying human needs. To do so there are 6 steps for Engineering-Focused Curriculum:
1. Defining the problem: Understand the need and constraints.
2. Developing solution: Evaluate various solutions to determine the best
3. Analyzing data: Define and specify problems, analyze the decisions of the design, predict the performance, determine the feasibility, evaluate alternatives and investigate failures
4. Modeling a solution: Product that can take any graphical, physical or mathematical representation. This process can enhance students’ understanding of conceptual knowledge and performance in engineering design
5. Conducting testing and modification
6. Optimization: Analyzing the options considering the constraints of the initial problem.

Teaching content
1. Detail a list of STEM subject knowledge items based on the project theme
2. Narrow the scope of knowledge based on learners competencies and on curriculum goals and relevant standards
3. Simulate students’ progress to identify stages that may entail learning difficulties
4. For those key stages provide students with relevant learning activities, suitable teaching strategies and support tools

Learning activities
There are two types of activities that facilitate the transition from abstract to tangible knowledge.
1. Inquiry and experiment activities (need to know)
1.1 Exploration and validation of scientific principles and their application as well as mathematical analysis
1.2 GOAL: help comprehend conceptual knowledge related to curriculum theme. This will enhance observational and analytical skills andstudents will perceive the efficacy of applying scientific principles to engineering practices.
1.3 Examples: Pinpoiting the problem (observation), data recording and analysis, assessment and communication with objective data
1.4 Skills: Defining a problem, analyzing and optimization
2. Design and making activities (need to do)
2.1 GOAL: Help understanding how to apply practical skills by concretizing abstract scientific principles and concepts
2.2 This will reinforce: Knowledge of materials, use of tools and equipment, model building and problem rectifying
2.3 Skills: Developing solutions, modeling and testing and modification

The two types of activities should be interspersed during the TLS. The paper presents an example on designing a “high pressure air racing car”.
One of the limits of this methodology could be the use of trial-and-error mechanisms in novice learners. Therefore, teachers should create activities to show the applicability of using science and mathematics knowledge for these purposes.

Point of Strength
This article goes beyond the theoretical framework of STEM projects design and exemplifies the theory with a real design. It is also interesting due to the detail used in the explanations of all the steps, improving the understanding of Engineering-Focused STEM projects.

DOI
https://doi.org/10.1007/s10763-020-10129-y

Keywords
Cross-disciplinary, Engineering design, STEM curriculum, Technology and engineering education