1.

INTRODUCTION

Astronomy has been taught at elementary school in France since 1985. The program of the grades 4-5 (French grade = cycle 3 for children from 8 to 11 years old), spread over 3 years, is focused on the solar system, asters motion and specifically of Sun, Earth and Moon. At these grades, most of the astronomical learning goals mobilize the understanding of the shadows origins observed on Earth (Night and Day alternation origins, Influences on season, and so on) and on Moon (e.g. Moon Phases and eclipses origins), in direct relationship with the positions of the asters in space.

However, in their efforts to make sense of the surrounding world, children learn informally explanations for many optical phenomena in daily life long (e.g. shadows origin, reflexion, night and day…) before official instruction are provided at schools. As a result, an abundance of knowledge is spontaneously formed before any formal learning takes place [10]. From a cognitive point of view, children construct their knowledge of the world and the universe on the basis of two information sources: observations of the world and explanations given by other people [29]. A lot of studies have shown that children and many adults of various cultures have difficulties in understanding contemporary scientific explanations of elementary astronomic phenomena [1, 8, 11, 16, 27, 30]. If the initial knowledge are integrated and consistently used, people tend to reinterpret the new information to form new synthetic models instead of scientific ones [11, 12, 31]. This can be a source of problems, especially when children’s preliminary knowledge radically differs from what is taught in school. Therefore, teachers have to propose pedagogical supports specifically oriented to overcome the barriers to learning. Teaching astronomical concepts can be an incredibly difficult task due to the need to switch points of reference to fully understand what is happening. Additionally, within constructivist views of learning, astronomy is difficult for students to explore. Currently, very few-targeted teaching material is available for teachers and learners in France. The available resources are mainly textbooks and physical models. Consequently, there is a real need to develop digital astronomical didactic materials. In order to overcome some barriers to learning, we have designed a Hybrid Environment dedicated to the learning of the Influence of Sun in the Solar System. This system, called HELIOS, is a tangible user interface for an Augmented Reality (AR) environment adapted to Inquiry-Based Sciences Education (IBSE). HELIOS, can thus be described as an Augmented and Inquiry-Based Learning Environment (AIBLE).

2.

THE NEED TO OVERCOME BARRIERS TO LEARNING

In the astronomy program of the primary school, one of the most difficult skills for children is to construct the causal relationship between the light source position and the relative position of the different asters in constant evolution. 4-5 grades children (8 to 11 years old), who are in full development of their spatial cognition, have many difficulties to assimilate geometric optical problems that are linked to astronomy [18, 19, 26].

Light is immaterial and imperceptible. Movement of non-material natural entities such as energy, heat or light are complex for children because they are detached from children’s perceptual experiences [2, 9, 10, 15, 17, 21]. For example, children frequently understand light as a concept centered on the light source. Therefore, they have many difficulties to locate light in space and most of them ignore the space in which light beams propagate [20]. Consequently, children do not spontaneously plan the form of different shadows because they do not understand the notion of rectilinear propagation of light. Therefore, teacher have to explain that the shadow which they see can be obtained by drawing lines leaving the light source and passing by the limit of the object. This requires 3D geometry skills and abstraction capacities.

However, at this stage of development, most of children still need concrete, topological information to construct mental images [18, 19]. For children from grades 4-5, all the evidences that structure the environmental perception for an adult are not totally developed. Children have to use topological spatial relationships (properties of single object or configuration) before being able to use projective or Euclidean representations.

Moreover, the geocentric position of child observations and the large scale of phenomena constitute barriers to understand astral motions and related influence of the Sun position on shadows that project onto Earth and Moon. To understand these phenomena, learners have to mentally construct a 3D perception of aster motions and to understand how light propagates from an allocentric point of view. However, 8-11 years children cannot access to large-scale space to observe and solve these types of astronomical problems.

Therefore, to enable children to understand astronomical phenomena, two kinds of conception fields are involved: 1- the objects motions and 2- the changes in objects, both related by cause and effect relationships with the primary light source position. Children have to mobilize optic and geometry knowledge and skills such as:

In this context, as in all activities involving physical knowledge, children actions on objects and their observations of the objects reaction are both important [13]. Therefore, manipulation of physical objects could provide valuable feedback to construct the causal relationship between the light source position and the shadows production on Earth and Moon. Moreover, learners should investigate and manipulate in order to become conscious of complex phenomena, change their misconceptions and construct scientific knowledge [5, 28]. Ideally, students will mobilize the skills required for scientific and technological inquiry for solving those problems [14, 23, 32].

Unfortunately, manipulations in astronomy are naturally impossible therefore require using models. Classical physical models (Fig. 1) constrain to work in a dark environment. With such models, the symbolism of the representation is low, and the important complexity of handling the physical elements affects the scientific learning for children [7, 22, 25]. Despite all of that, those types of models are still used because little alternatives exist.

Figure 1.

Example of a physical model used in primary classroom to teach the origin of the Day/Night on Earth. It is simply composed of plastic balls and a light bulb.

3.

AIBLE-HELIOS®, AN AUGMENTED REALITY AND TANGIBLE INTERFACE

AIBLE-HELIOS® is based on augmented reality and tangible interaction. The goal of Augmented Reality is to embed virtual objects into the real world. To do so, several technologies exist. One is to use see-through Head-Mounted-Displays (HMD). Another is to project directly digital content onto physical objects (spatial augmented-reality). These two approaches can provide rich user experiences. However, they are too complex to be implemented concretely in a classroom. Consequently, we chose a simpler implementation of AR where a camera films the real environment. The recorded video stream is augmented with virtual objects, and the resulting images are displayed on a screen in real-time (See Figure 3).

Figure 2:

design principles

Figure 3:

A) Example of first person perspective of the AR environment. B) Detail of the terrestrial observer associated to the viewport. C) optional display of meridians. D) Example of manipulation producing a solar eclipse on the African continent.

Visual guides support learners: (a) dashed-lines between bodies’ centers (b) a terrestrial observer (c) Viewport showing the terrestrial observer’s view in real-time.

In HELIOS, users manipulate the virtual asters by physically moving markers, following a tangible approach. Tangible interaction is “an emerging post-WIMP (Windows, Icons, Menus and Pointer) approach that is concerned with providing tangible representations to digital information and controls” [24]. One of the strengths of tangible interface is their “situatedness”: interaction takes place in a real- world environment that often hides most of the technological aspects to

Tangible User Interfaces (TUIs) involve gesturing, physical movement and embodiment [4] that play an important role in our learning goals. Gestures associated to TUIs can provide external representations of a problem or an object, which play a role in problem solving and learning. It corresponds to the possible enactments of concepts by students [3].

4.

FUTURE WORKS

In the future, we will continue enhancing the functionalities of AIBLE-HELIOS®. We will also conduct experiments that take into account full professional constraints. This includes the fact that all children will work at the same time and the possibilities for teachers to conduct their own learning activities using this tool.