Science and Chemistry in Primary Education in Spain: Curricular Regulation, Pedagogical Foundations, and Experimental Activities

1. Introduction

Early contact with natural sciences and chemistry during Primary Education plays a crucial role in shaping how pupils understand physical reality and construct scientific explanations about daily phenomena (Bybee, 2014; Harlen, 2018). Far from being a passive accumulation of facts, science and chemistry learning at this stage should foster systematic observation, curiosity, hypothesis formulation, and evidence-based reasoning. Within the curriculum of Natural Sciences, chemical concepts and physical phenomena offer an exceptional framework for engaging pupils aged 8 to 12 in meaningful learning, as they provide immediate, visible, and tangible evidence of natural principles.

Despite its recognized value, integrating regular practical science in primary classrooms faces well-documented challenges, including resource availability, curriculum density, and severe time constraints (Hodson, 2014; Osborne, 2015). Consequently, experimental activities are often designed as brief observational demonstrations to reinforce theoretical concepts, as full inquiry sequences that foster cognitive conflict and conceptual progression typically require instructional time that is rarely available in daily classroom practice.

To address these challenges, this article presents a comprehensive examination of primary science and chemistry education in Spain. The work bridges the gap between national curricular mandates and classroom practice by connecting the current legislative framework with a solid pedagogical foundation based on the Predict-Observe-Explain (POE) model. Furthermore, a practical sequence of ten structured experimental activities —carried out in a primary school setting— is detailed to illustrate how low-cost materials can be effectively leveraged to promote scientific competence and reasoning in pupils aged 8 to 12.

Against this background, the present article has two complementary aims: first, to examine the role of experimentation in Natural Sciences and Chemistry education in Spanish Primary Education; and second, to present a practical school-based experience in which simple scientific experiments were used with Primary Education pupils at the Colegio Español Ramón y Cajal in Tangier, Morocco.

2. Legislative and Pedagogical Framework

2.1. Science Education in Spanish Primary Education: Legislative Framework

The Spanish educational framework has progressively moved from a predominantly content-centred conception of education towards a competence-based approach. Organic Law 3/2020 (LOMLOE) reinforces the development of competences and meaningful learning and establishes the current legal framework within which Primary Education is organised (Ley Orgánica 3/2020).

Royal Decree 157/2022 is particularly relevant to science education (Real Decreto 157/2022). It identifies competence in mathematics, science, technology and engineering as one of the eight key competences of the curriculum. The definition of STEM competence explicitly refers to understanding the world through scientific methods and includes observation and experimentation as methodologies for asking questions and drawing conclusions based on evidence.

The Royal Decree also establishes operational descriptors for the end of Primary Education. In particular, descriptor STEM2 states that pupils should use scientific thinking to understand and explain phenomena around them, use appropriate tools and instruments, ask questions and carry out simple experiments in a guided manner. The curricular framework therefore does not regard experimentation as an optional enrichment activity; rather, it forms part of the scientific competence that pupils are expected to develop.

The specific competences of the area related to knowledge of the natural, social and cultural environment reinforce the same principle. Pupils are expected to formulate questions and predictions, search for reliable information, design and carry out guided experiments when required, make observations and measurements, analyse results, compare them with predictions and communicate the conclusions reached.

The basic knowledge associated with scientific culture similarly includes procedures of inquiry, observation, classification, pattern identification, model construction and experiments involving control of variables. These elements show that the current curriculum is compatible with an inquiry-based and experimental approach to science education.

Thus, the legislative framework provides strong curricular support for practical science activities in Primary Education. The challenge is not whether experimentation is compatible with the curriculum, but how teachers can use it effectively and safely to produce meaningful scientific learning.

2.2. Curricular Organization, Time Allocation, and Classroom Constraints

Despite the explicit curricular support established in Royal Decree 157/2022, the structural organization and weekly time allocation assigned to Natural Sciences present notable constraints in daily school practice. Regional implementations in Spain generally allocate between 1.5 and 2 hours per week to Natural Sciences in Primary Education. This figure derives from the regional decrees developing Royal Decree 157/2022 (e.g., Decreto 106/2022 de la Comunitat Valenciana, Decreto 155/2022 de Galicia, Decreto 209/2022 de Andalucía), not from international reports. For a review of time constraints in other contexts, see Banilower et al. (2018) and, for the Spanish context, Cañal (2012) and Vázquez-Alonso & Manassero-Mas (2018).

This limited time allocation must accommodate an extensive set of basic contents (“saberes básicos”), ranging from human anatomy and biodiversity to physical and chemical transformations. Consequently, teachers face significant pressure to cover theoretical topics, which frequently leads to prioritizing expository teaching methods over hands-on laboratory work. Reconciling the ambitious competence-based goals of the LOMLOE with the reality of tight weekly schedules requires instructional strategies that integrate simple, low-cost experimental activities directly into regular classroom routines.

2.3. The Role of Experimentation, Cognitive Conflict, and POE Sequences

To overcome the limitations imposed by reduced time allocations, practical science instruction must rely on structured pedagogical models that maximize conceptual engagement. Simply performing a demonstration does not guarantee meaningful learning if pupils remain passive observers.

The Predict-Observe-Explain (POE) model provides an effective framework for embedding experimentation into regular primary lessons (Haysom & Bowen, 2010; White & Gunstone, 1992). By asking pupils to predict the outcome of a physical or chemical phenomenon before it occurs, the teacher activates prior knowledge and generates a cognitive conflict when the observed result contradicts initial expectations. This dissonance drives pupils aged 8 to 12 to reconstruct their mental models through guided explanation and evidence-based reasoning, transforming brief low-cost experiments into powerful tools for developing scientific competence. For examples of argumentation and critical thinking supported by POE-type strategies, see Juntunen and Aksela (2014) and Vieira & Tenreiro-Vieira (2016).

3. Methodology and Contextual Setting

3.1. School Context and Institutional Setting

The instructional proposal was implemented at the Colegio Español Ramón y Cajal in Tangier, Morocco. This institution belongs to the network of Spanish state-owned educational centers abroad (Centros de Titularidad del Estado Español en el Exterior), managed directly by the Spanish Ministry of Education, Vocational Training and Sports. Consequently, the center adheres strictly to the official Spanish national curriculum governed by Organic Law 3/2020 (LOMLOE) and Royal Decree 157/2022.

The implementation was carried out across classes in the Middle and Upper cycles of Primary Education, involving about 300 pupils aged 8 to 12 (3rd to 6th grades). No personal data of pupils were collected. The student body in this international state-school setting is linguistically and culturally diverse, which underlines the importance of employing visual, practical, and hands-on teaching strategies to facilitate scientific comprehension beyond purely textual methods.

3.2. Safety Measures

Given that some activities involve an open flame (4.1 The Flame and the Water Shield, 4.6 Upside-Down Smoke, 4.8 Fireproof Balloon) and heat treatment of enamelled wire (4.9), strict safety measures were applied: all demonstrations involving flame were performed solely by the author, with pupils kept at a minimum distance of 1.5 m, using a protective tray, gloves, and a fire blanket and water nearby. Balloons with water were handled to avoid scalding; the enamel removal from copper wire was performed by the teacher outside pupil reach, with ventilation, and pupils only manipulated cold, prepared wires. No pupil handled matches, lighters, hot materials, or electrical sources directly. Electrical activities used low-voltage batteries (≤4.5 V) and were supervised continuously.

3.3. Design Criteria for Low-Cost Experimental Sequences

To ensure that practical science activities could be seamlessly integrated into the regular schedule without disrupting the curriculum, the design of the experimental sequence was guided by four main pedagogical and operational criteria:

• Time Efficiency: Each activity was planned to fit within a 15-to-20-minute window, leaving sufficient time within the weekly 1.5-to-2-hour Natural Sciences allocation for introductory contextualization and subsequent consolidation.
• Low-Cost and Everyday Materials: Experiments utilized accessible, safe, and non-toxic household items (e.g., vinegar, baking soda, food coloring, plastic bottles, vegetable oil, magnets) (Abrahams & Millar, 2008; Cañal, 2012).
• Instructor-Led Safety and Feasibility: Procedures were designed to be demonstrated by the instructor while actively involving pupils in prediction, systematic observation, and guided measurement, ensuring full compliance with classroom safety standards.
• Alignment with Basic Contents (“Saberes Básicos”): The activities directly addressed fundamental physical and chemical principles required by Royal Decree 157/2022, such as matter properties, density differentials, changes of state, thermal absorption, surface tension, and chemical reactions.

3.4. Methodological Application of the POE Model

• Predict: Before initiating any physical demonstration, the author presented the experimental setup. Pupils were prompted to formulate individual predictions regarding the expected outcome, alongside a brief justification of their reasoning.
• Observe: The instructor carried out the experimental procedure. Pupils closely monitored the physical or chemical phenomenon, recording observable evidence and noting any discrepancies with their initial predictions.
• Explain: Through guided whole-class discussion, pupils compared their prior hypotheses with the observed reality. The author scaffolded the dialogue to help pupils resolve the resulting cognitive conflict and construct evidence-based scientific explanations (Driver et al., 2014; Mercer et al., 2004).

4. Examples of Natural Sciences and Chemistry Experiments in Primary Education

A wide variety of simple experiments from the fields of Natural Sciences and Chemistry can be implemented in Primary Education classrooms using inexpensive, readily available materials. These activities are designed to stimulate student inquiry, prediction, and child-led hypothesis testing through direct observation of the procedures executed by the researcher. Rather than presenting abstract formulas, the following ten experimental interventions are structured to guide pupils through direct observation, forcing them to confront their preconceptions and build logical scientific reasoning:

4.1. The Flame and the Water Shield

To spark a debate on how everyday objects handle heat, children were asked to predict what would happen if a plastic cup touched a flame. The author first held an empty cup over a flame, allowing pupils to observe it catch fire and melt immediately. Next, the author tested a cup half-filled with water over the same heat source. Pupils watched in surprise as the fire consumed the plastic but stopped abruptly exactly at the water level, leaving the bottom intact. Children's interpretation: water acts as a 'heat shield' or coolant. Scientific note: water has high specific heat capacity and latent heat of vaporization; it absorbs heat and keeps the temperature at the cup-water interface below the melting point of the plastic.

4.2. Finding Clues of a Chemical Change (The Foaming Volcano)

This activity was designed to help children differentiate between simply mixing ingredients and creating a true chemical transformation. Using a small bottle on a tray, the author mixed water and baking soda, and then poured vinegar into the container. The children actively looked for physical signs of change as the demonstration unfolded. They observed the sudden production of gas, which generated a rapid rush of bubbles and foam spilling over the top. Pupils used this visible evidence to conclude that a new substance (gas) had been born from the interaction. Scientific note: acetic acid reacts with sodium bicarbonate to produce sodium acetate, water and carbon dioxide (CO₂); the release of CO₂ indicates a chemical change.

4.3. The Saltwater Lift: Heavy and Floating Objects

This experiment challenged the common assumption among primary students that heavy objects always sink. Pupils were presented with two jars of water—one plain and one heavily salted—prepared for the demonstration. After formulating their predictions, they observed the fresh egg being placed into both jars, seeing it sink in the plain water but float in the salted jar. Children's reasoning: dissolving salt changes the property of the water itself, making it denser. Scientific note: adding salt increases water density and thus buoyant force (Archimedes' principle). When solution density exceeds egg's average density, the egg floats.

4.4. Breaking the Boundary Between Water and Oil

Aimed at introducing mixtures to 3rd and 4th graders, this setup explored why some liquids do not mix. Water and vegetable oil were combined in a container and shaken to force a union. Pupils observed that the oil always climbed back to the top, forming a sharp boundary line. Upon adding a few drops of liquid soap and shaking the container a second time, children noticed that the boundary vanished into a single cloudy liquid. Children's interpretation: soap acts as a bridge. Scientific note: water and oil are immiscible due to polarity differences. Soap is a surfactant with hydrophilic and hydrophobic ends that reduces interfacial tension, allowing formation of an emulsion.

4.5. The Chain of Magnetic Forces

To help pupils visualize invisible forces, a strong magnet was used to attract a single metal coin before the class. A second coin was then attached to the first, allowing children to discover that the magnetic power traveled through the metal, turning the first coin into a temporary magnet. As hanging chains were progressively formed and different types of coins were compared, pupils noted that some metals worked better than others. By observing coins being added until the chain broke, pupils empirically discovered a physical limit: the further away from the main magnet, the weaker the invisible pull became. Scientific note: this illustrates induced magnetism in ferromagnetic materials and that magnetic field strength decreases with distance.

4.6. Flipping Predictions: The Upside-Down Smoke

This intervention was specifically designed for older primary pupils (5th and 6th grades) to create cognitive conflict by disrupting their daily observation that smoke always rises. To execute the demonstration, a paper tube was inserted into a small hole near the top of an empty plastic bottle and lit from the outside. Instead of floating upward, the smoke poured out of the inner end of the tube and fell straight to the bottom like a heavy liquid waterfall. Pupils deduced that without rising air currents inside the closed bottle, the smoke became cold, trapped, and heavy enough for gravity to pull it downward. Scientific note: normally warm smoke rises due to convection (lower density). In the closed bottle, smoke cools quickly, contains heavier aerosol particles and CO₂, and descends as it is denser than air.

4.7. The Arrow Illusion: Bending Light with Water

This optical experiment engaged all primary cohorts by playing with visual perception. Pupils looked through a clear glass of water at a paper backdrop showing two colored arrows (a red one pointing left and a blue one pointing right). As the paper was slowly moved away from the glass during the setup, the children saw the arrows suddenly flip and point in opposite directions. Children's hypothesis: passing through a round glass of water bends the light rays inward. Scientific note: the cylindrical glass filled with water acts as a convex lens; refraction at interfaces inverts the image when object distance exceeds focal length (Snell's law).

4.8. The Fireproof Balloon Test

To reinforce the idea of water as a heat absorber, pupils observed the comparative resistance of two rubber balloons held over a candle flame. They predicted that both would pop. The air-filled balloon burst instantly upon touching the flame. However, the balloon containing a small pool of water remained whole, merely gathering a black soot mark. Children's reasoning: water pulls heat away from thin rubber. Scientific note: water's high thermal conductivity and specific heat keep rubber temperature below melting point, while air does not.

4.9. Awakening a Metal Screw with Electricity

This final project combined electricity and magnetism while teaching children the value of precision when building scientific setups. A copper wire was wrapped tightly around an iron screw to form a coil. Pupils learned that the wire possesses an invisible insulating enamel coating that blocks electricity, requiring the tips to be carefully burned and scraped clean by the teacher before connecting to a battery. When the connection was established, the screw suddenly became alive with magnetic force, picking up paperclips. This demonstration was highly educational because when trial setups were intentionally tested without thoroughly cleaning the wire tips, the magnet failed to work, prompting immediate troubleshooting. Scientific note: current through the coil creates a magnetic field (electromagnet); the enamel is polyurethane/polyester insulation, not plastic, and must be removed to ensure continuity.

4.10. Illuminating a Simple Circuit: The Bulb and Battery Challenge

To introduce 3rd and 4th graders to the fundamental concept of an electric circuit, a simple direct-current setup was demonstrated using a standard battery, a small light bulb, and a single copper wire with stripped ends. Pupils observed as the base of the bulb was placed directly onto one battery terminal, while the bare wire was connected from the opposite terminal to touch the metallic casing of the bulb. The immediate illumination provided clear visual proof that electricity requires an uninterrupted conductive pathway. This allowed students to conceptualize open vs closed circuit, deducing that electric current must both leave and return to the power source. The battery supplies electrical energy; the current transfers this energy to the bulb where it is transformed into light and heat. The current itself does not generate energy.

5. Discussion

The integration of practical science in Primary Education remains a central challenge in educational systems governed by dense curricula and limited weekly schedules. The present instructional proposal illustrates that aligning simple, low-cost experimental activities with the current Spanish regulatory framework (LOMLOE; Royal Decree 157/2022) offers a viable pathway to foster scientific competence in pupils aged 8 to 12 without exceeding classroom constraints. These observations suggest, rather than demonstrate conclusively, potential benefits that would require systematic evaluation.

A primary constraint identified in the literature and reflected in the Spanish context is the scarce time allocated to Natural Sciences—typically 1.5 to 2 hours per week according to regional decrees implementing Royal Decree 157/2022. Conventional laboratory sessions often require specialized infrastructure, long preparation times, and extended instructional blocks, which frequently leads teachers to omit practical work altogether. The implementation of the ten low-cost experimental sequences suggests that short, targeted experimental demonstrations lasting 15 to 20 minutes can bridge this gap.

Furthermore, the qualitative observations suggest the pedagogical potential of structuring experiments around the Predict-Observe-Explain (POE) model rather than relying on purely expository teacher demonstrations. When pupils are prompted to record explicit predictions prior to an experiment, they activate intuitive preconceptions. The subsequent observation of unexpected behaviors may create a cognitive conflict that stimulates active reasoning (Kang et al., 2004; Limon, 2001). Rather than passively absorbing facts, pupils engage in qualitative argument construction to reconcile predictions with observable evidence (Osborne & Patterson, 2011; Vieira & Tenreiro-Vieira, 2016). This approach illustrates a possible way to foster reasoning, without claiming measured effectiveness.

Finally, while this work provides a grounded qualitative framework and a practical sequence of ten adaptable experiments, certain limitations should be acknowledged. The study presents an instructional proposal evaluated through qualitative classroom observation rather than quantitative comparative metrics. Future work could complement this approach by designing standardized tools to measure quantitative impact.

6. Conclusions

• Curricular Alignment: The current Spanish legislative framework explicitly positions scientific inquiry and experimentation not as optional enrichment, but as core components of the STEM competence (specifically STEM2).
• Overcoming Time Constraints: The primary barrier—the limited weekly schedule of 1.5 to 2 hours—can be mitigated through short, 15 to 20-minute experimental sequences that utilize low-cost, household materials. This illustration suggests feasibility, not measured efficacy.
• Potential of the POE Model: Structuring practical activities around the Predict-Observe-Explain sequence illustrates how simple demonstrations may become active learning opportunities. Generating cognitive conflict may prompt pupils to articulate preconceptions and construct evidence-based explanations. Further empirical evaluation is needed.
• Practical Viability: The qualitative implementation suggests that inquiry-based experiments are feasible within regular routines, potentially promoting scientific literacy without overloading the curriculum.

In summary, bridging the gap between legislative ambitions and classroom reality does not require extensive resources, but rather targeted pedagogical strategies that embed low-cost experimentation into structured conceptual sequences. This proposal should be understood as illustrative practice, not as evidence of learning gains.