Lesson objective: Understand that we can compare tenths and hundredths written as fractions or decimals.

Students bring prior knowledge of comparing fractions from 3.NF.A.3. This prior knowledge is extended to comparing fractions and decimals as students conceptually compare decimals so that they can choose the cooler temperature to go on vacation. A conceptual challenge students may encounter is comparing decimals to different place values (i.e. thinking 4.5 < 4.43 because 4.5 has less digits).

The concept is developed through work with base ten flats, which allow students to compare two decimals side by side to show magnitude of the number.

This work helps students deepen their understanding of equivalence because it allows us to be flexible with equivalent forms of numbers and represent relationships among quantities.

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they compare the temperature each day over the course of one week to discover the cooler temperature to help them choose which week they should go on vacation.

**Key vocabulary: **

- decimal
- denominator
- equivalent
- flat
- greater than
- less than
- model
- numerator
- representation
- rod
- unit
- tenths
- hundredths
- whole

**Special materials needed:**

- base 10 manipulative
- paper copies of flats
- paper copies of rods
- tiles