Base ten blocks are an amazing (and underused) tool to help students understand decimals. To get started, your students will have to develop some new understanding. Until now, they have probably understood base tens as ones, tens, and hundreds.
But now, since they are older and learning more complex skills, we will use them differently. For the purpose of decimals, we will see these blocks as wholes, tenths, and hundredths. As shown by the picture below, the hundreds block will now represent one whole. The tens block represents one-tenth (because it is one-tenth of the whole or ten times smaller than the whole). The ones block represents one-hundredth because it is one-hundredth of the whole or one-hundred times smaller than the whole.
Your students will need time to develop this new understanding, so be sure to give them lots of time to work with base tens in this new way. Lots of activities are included below!