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This experiment determines the stoichiometry of the reaction of a carbonate or hydrogen carbonate and HCl by measuring the pressure of the CO2 produced using a Vernier pressure sensor, Texas Instruments CBL interface, and a TI-82/83 graphing calculator. Various amounts of the carbonate are reacted with a constant amount of HCl. The change in pressure in a constant-volume (20-oz soda bottle) system is measured and plotted against the mass of the carbonate. The mass of the carbonate that is needed to react with all the HCl is determined from the graph. The mole ratio between the carbonate and HCl in the reaction mixture is determined and used to write a balanced equation for the reaction. Different carbonates and hydrogen carbonates have been used successfully. The advantages of this procedure are that students can run a large number of samples (since each sample requires only 100 s of data collection time), develop an understanding of the concept of a limiting reactant, and develop an understanding of the relationship between the amount of gas produced by a reaction and the pressure in the reaction container. The experiment incorporates the use of technology, graphing, and data analysis and is appropriate for an introductory chemistry laboratory. The directions can be easily modified to use computers and other graphing calculator probe systems.

Young children’s spatial reasoning is critical to mathematics learning from an early age. Recent reviews have drawn attention to the importance of mathematical experiences in the early years; however, an explicit focus on research in spatial reasoning can contribute to a more coherent account of the field. This paper reports a scoping review of qualitative studies (n = 37) during the years 2009–2021. The studies analysed in this review provide insight into children’s embodied spatial concepts and non-verbal expressions such as gesture and the relationship between spatial reasoning and mathematics learning in early childhood (birth to 8 years). Four main themes were found: (i) children’s manipulation and transformation of objects, (ii) children’s bodily engagement with and within spaces, (iii) children’s representation and interpretation of spatial experiences, and (iv) contexts for spatial learning. While the review illuminates a deeper awareness and a more holistic and embodied view of children’s spatial competencies, there remains few studies focussed on children under three years of age. Future directions for ongoing research are identified.