Mini-Lakes: A Long-Term Investigation

InvestigationWhat students do with the mini-lakeHow students use mini-lake data to track transformations of matter
Inv. 1 Measuring materials for lake in containers Measure weight of materials: sand, gravel, rocks, water, container and top Understand that weight is a reliable indicator of gains or losses of matter in the mini-lake system

Understand that in a closed system nothing is added and nothing is taken away

Seek explanations for any changes in the weight

Plot data points on line graph to make a picture at tells the story of change in weight over time

Use measurement to calculate the amount of salt added

Track rate of evaporation

Reason about how they will know when all of the water has evaporated that only water evaporates and solid matter is conserved
Inv. 2 Pouring water into mini-lake Measure volume of mini-lake materials

Build mini-lakes

Completed mini-lake on scale Weigh mini-lake and record measurements in a data table
Inv. 3 Class discussion circle Compare heaviness-for-size of water and sand (For water: 1g=1cc)
Inv. 4  
Inv. 5 Students adding salt to mini-lake Transform mini-lakes to salt lakes
Inv. 6  
Inv. 7 Student with uncovered mini-lakeUncover the mini-lake thus changing from closed to open system
Inv. 8  
Inv. 9-16 Students weighing dried mini-lakeContinue to collect and graph weight data until all the water has evaporated (weight of solid materials is conserved)
Inv. 17 Annotated mini-lake graph with visible explanationsRecognize that the line graph represents changes in their actual mini-lakes over time Annotate the mini-lake graphs to “tell the story” of transformations of in the mini-lake over time

Use the particle model to explain dissolving salt and evaporation of water