Recently both the 7th and 10th grade were scheduled to study chemistry in their morning block schedule, and the blocks for both grades included the topics of acids, bases and salts, crystallization and metals and their properties. The chemistry teachers decided to spend a morning teaching the two grades together even though the 7th grade developmental approach is distinctly different to that of the 10th grade. The students worked in lab teams with 10th graders as team leaders. We used hydrochloric acid to displace the sulphur in different concentrations of sodium thiosulphate. The next day the 7th grade the reflected and understood that the length of time for the reaction was affected by concentration. The more concentrated the solution the quicker the reaction time! In contrast, the 10th grade calculated the specific concentrates and noted the times and then went on to plot their results as a rate, using the resulting graph to draw a number of conclusions. This is a step in their studies toward topics such as Avogadro’s number, molarity and the particulate theory of matter. It was a lovely opportunity to be working in this way which allowed us to explore concepts together through direct experience and challenging them to stretch in developmentally appropriate ways. The 7th grade students, walking back to class, were busy calculating what grade their 10th grade team leader would be when they joined the High School and what class they might be helping when they were in 10th grade!