The lesson saw our students exploring heat gain and heat loss via a mercury thermometer. We taught them what parallax error is and how to read the readings off a thermometer accurately. They got to see for themselves what happened to the readings when the thermometer is dipped into hot water and iced water. They were intrigued to observe that mercury expands when heated and contracts when cooled in different temperatures. After observation, they got down to complete their investigative task work and wrote down their reflections.