This lab is suited for a first year chemistry student and is a great way to model isotopes, relative abundance and atomic mass for an element. The resource is completely adaptable - you can tweak and make changes as necessary to best suit your classes. The lab includes teacher notes with suggestions on how to adapt and expand, a thorough background for students, materials (with photos), pre-lab questions with hypothesis, detailed procedure, data table, calculations (with formulas provided) and analysis questions.
In my school with one hour classes, this lab takes on average one and 1/2 classes (90 minutes). Additionally, this resource comes with the teacher answer key!
All materials can be easily found within your classroom or even at home. It does not require anything special and no technology beyond a balance.
Students will surely comprehend the concept of isotopes through this hands-on modeling lab.