Time is a measurement that helps us understand the duration, sequence, and intervals of events. It is an essential concept for organizing our daily activities and understanding the world around us.

There are various units of time used for measurement. The basic units include:

- Seconds (s): The smallest unit of time, often used for measuring short durations.
- Minutes (min): Equal to 60 seconds.
- Hours (h): Equal to 60 minutes or 3,600 seconds.
- Days: Equal to 24 hours or 1,440 minutes.
- Weeks: Equal to 7 days.
- Months: A unit of time based on the lunar calendar, varying between 28 to 31 days.
- Years: Equal to 12 months.

When reading and writing time, we use the 12-hour clock and the 24-hour clock format. In the 12-hour clock, the day is divided into two 12-hour periods: a.m. (ante meridiem) and p.m. (post meridiem). The 24-hour clock, also known as military time, uses a continuous count of hours from 0 to 23.

To tell time on an analog clock, the hour hand represents the hour, the minute hand indicates the minutes, and the second hand shows the seconds. On a digital clock, the time is displayed in hours and minutes using numbers.

Calculating time involves adding, subtracting, and converting time units. When adding or subtracting time, it's important to regroup minutes if they exceed 60 or hours if they exceed 24. Converting time units involves changing between seconds, minutes, hours, and days based on their relationships.

To master the concept of time, consider the following study tips:

- Practice reading analog and digital clocks to improve time-telling skills.
- Use real-life scenarios to solve time-related word problems.
- Create a timeline of events to understand the sequence of time.
- Practice converting between different units of time using conversion charts and exercises.
- Use online resources and interactive games to reinforce time concepts.

Study GuideDecimals/Fractions Activity LessonOrdering Decimals & Fractions Activity LessonPercent Grids Activity LessonFraction & Percent Circles Worksheet/Answer key

Decimals/Fractions Worksheet/Answer key

Decimals/Fractions Worksheet/Answer key

Decimals/Fractions Worksheet/Answer keyDecimals/Fractions Worksheet/Answer keyPercent Grids Vocabulary/Answer keyDecimals/Fractions

Number and Operations (NCTM)

Understand numbers, ways of representing numbers, relationships among numbers, and number systems.

Develop understanding of fractions as parts of unit wholes, as parts of a collection, as locations on number lines, and as divisions of whole numbers.

Recognize and generate equivalent forms of commonly used fractions, decimals, and percents.

Algebra (NCTM)

Use mathematical models to represent and understand quantitative relationships.

Model problem situations with objects and use representations such as graphs, tables, and equations to draw conclusions.

Grade 4 Curriculum Focal Points (NCTM)

Number and Operations: Developing an understanding of decimals, including the connections between fractions and decimals

Students understand decimal notation as an extension of the base-ten system of writing whole numbers that is useful for representing more numbers, including numbers between 0 and 1, between 1 and 2, and so on. Students relate their understanding of fractions to reading and writing decimals that are greater than or less than 1, identifying equivalent decimals, comparing and ordering decimals, and estimating decimal or fractional amounts in problem solving. They connect equivalent fractions and decimals by comparing models to symbols and locating equivalent symbols on the number line.