Explanation Videos For Grade 1

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Grade 1 Semester 1


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Semester 1 Week 1 – Numbers to 10

In this lesson, students develop number sense through counting, representing numbers, and comparing values. Starting with basic counting skills, students learn to look at picture representations of numbers (e.g., a picture of 5 balls represent the value of the number 5), and are able to identify the values of those numbers, read and write the numbers, and compare the values. Applied skills include one to one correspondence, subitizing, number pattern identification, and ordering numbers.

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Semester 1 Week 2 – Number Bonds

Number bonds are efficient, meaningful representations of parts and wholes. Like ten frames, they are useful in building understanding and practice of addition and subtraction concepts, within one visual reference. Students can use number bonds to learn how addition and subtraction are inverse operations, while developing addition and subtraction fact family fluency.

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Semester 1 Week 3 – Addition Facts to 10

Addition Facts to 10 teaches counting on, which is essentially adding by one, increasing the total as students count. Students count objects, use pictorial representations, then apply these skills with printed numbers. They learn that addition means to add a given number onto an initial number, and that these two parts equal their combined values, thus introducing the meaning of the equal sign as requiring equivalence and not indicating a next step. Teach students to actively apply the properties of addition, and practice adding different combinations to 10. They will also determine the missing numbers in different locations within a number sentence, using number bonds. 

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Semester 1 Week 4 – Subtraction Facts to 10

The concept of subtraction centers around the difference between a larger and a smaller number. Students will learn that one part is taken away from a larger whole, and the order of these cannot be reversed. Counting back is a useful tool to introduce this concept, since numbers become smaller in value when counting backwards, Students can practice this concretely on a ten frame or pictorially with a number line. As in addition, students should reinforce understanding of parts equalling a whole. In subtraction they are determining the unknown whole number. They continue to practice understanding the concept of equal, since the value of a part removed from a whole equals the remaining part.

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Semester 1 Week 6 – Numbers to 20

In this lesson, students apply both base ten and place value understanding, as they extend their counting past ten. Numbers are represented by place value: tens and ones. It is important to show students that ten individual ones can be grouped into a ten (a group of ten ones), to help them visualize the value of the whole number. With this knowledge, students can base their knowledge of numbers off of ten and then compare two digit number values, and determine patterns in number sequences.

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Semester 1 Week 8 – Addition within 20

Students are taught to use more efficient strategies to add numbers with sums up to 20. Strategies include counting on from the highest number understood, adding by place value tens and ones, decomposing numbers to first form a ten, then adding on the remaining value, and creating equivalent but known sums. Learning these strategies helps to develop fluency in basic addition facts, while also teaching students how to use their knowledge of numbers to solve the problem. Students can then progress to more complex concepts, such as finding a missing added, which ties into subtraction.

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Semester 1 Week 12 – Subtraction within 20

Students are taught to use more efficient strategies to subtract numbers from totals up to 20. Strategies include counting backwards from the starting number, subtracting by place value tens and ones, decomposing numbers to result in ten, then subtracting the remaining value, and using the relationship between addition and subtraction. Students can use these strategies to develop fluency in basic subtraction facts, which mirror addition facts. Developing fact fluency and using efficient strategies is important to effectively solve word problems. 

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Semester 1 Week 16 – Addition and Subtraction Word Problems

Teach students to efficiently solve word problems requiring addition and subtraction to totals of 20. Introduce students to bar modeling which represents known and unknown values, and can be taught in both the concrete and pictorial levels. Bar modeling is extremely effective in representing all types of addition and subtraction problems, able to represent any unknown value: sum, missing addend, difference, minuend, or subtrahend. 

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Semester 1 Week 18 – *Ordinal Numbers and Positions

In this lesson, students learn how to describe the position of physical or picture representations of objects in a line in relation to a reference point. Ordinal number based questions can be used as a springboard for students to use logic in determining additional information.

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Grade 1 Semester 2


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Semester 2 Week 1 – Shapes

Student will learn about attributes of shapes, using various manipulatives to form two and three dimensional shapes. They will learn how to see equal parts of two dimensional shapes, using fractional terms such as whole, parts, equal, and fractional units, setting a foundation for working with fractions.

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Semester 2 Week 3 – Numbers to 40

Counting to 40 enables students to add onto foundational skills of adding on and basic place value. Students will practice skip counting by smaller groups of twos or tens, which will prepare them for multiplication in future years. They will use place value skills to decompose and regroup numbers into new combinations without changing the original value, thereby strengthening place value understanding. Students will be comparing numbers values and learning how to communicate their understanding using symbols to represent relative size of numbers. They will also work on identifying patterns in number sequences.

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Semester 2 Week 4 – Addition within 40

Add numbers with sums up to 40, with and without regrouping. Strategies focus on adding by place value tens and ones, decomposing numbers to first form a ten, then adding on the remaining value. Students can use references such as place value charts, number lines, and number bonds to reinforce their practice. Students must understand place value in order to progress to addition using the standard algorithm.

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Semester 2 Week 6 – Subtraction within 40

Using models based on place value understanding and the relationship between addition and subtraction, students will solve subtraction problems with totals from 40. Students will learn to use effective strategies to subtract numbers with and without regrouping, including place value charts, number lines, and number bonds to reinforce practice. Students must understand place value in order to progress to addition using the standard algorithm.

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Semester 2 Week 8 – Adding Three Numbers, Word Problems

Students will work on addition problems with three addends, using specific strategies based on simpler concepts. Students will learn to first identify two of the three numbers that add to ten, or to regroup numbers so that there is a ten to work with. When working on word problems, students need to solve situations on adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions.

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Semester 2 Week 9 – Measurements: Length

In this lesson, students use knowledge of number sizes to read different units of measurement. First, students will compare and order lengths using standard and non-standard units. Encourage students to use logical reasoning to work out solutions. Students will also learn measurements of time in hour and half hour units. Finally, students will work on interpreting and using data to solve problems.

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Semester 2 Week 11 – Mental Math Strategies

Building up mental math skills requires students to apply number sense, logical reasoning, and efficient math strategies based on base ten and place value knowledge. Using mental math helps students to strengthen fact fluency in addition and subtraction, and reinforces their problem solving processes. Additionally, applying mental math strategies can be useful when students explain their solutions.

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Semester 2 Week 13 – Numbers to 100, Addition within 100, Subtract within 100

In this lesson, students count to 120, using the logic and patterns of numbers presented in a hundreds chart and other strategies. Students may group numbers by smaller set units which can also assist in estimation skills as size of numbers are more visible. Using related skills, students can practice adding and subtracting on a number line or by using place value understanding to identify number patterns. Students also compare larger two digit numbers and use symbols to represent relative size of the numbers.

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Semester 2 Week 14 – Numbers to 100, Addition within 100, Subtract within 100

This lesson focuses specifically on subtraction of numbers within 100. When regrouping is not required, values can simply be subtracted by place value, ones subtract ones and tens subtract tens. It is important that numbers are notated accurately according to their place value. When regrouping is required, students must understand the concept of regrouping numbers without changing the values of the numbers. In order to effectively use the standard algorithm, teachers should ensure that students understand regrouping.

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Semester 2 Week 15 – *Money (Optional)

Students will build foundational monetary skills by learning to identify coins and their respective values. They will be able to represent equivalent values of given coins through combinations of another type of coin. Students should apply these skills to real life contexts through word problems and games.

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Semester 2 Week 17 – *Multiplication and Division (Optional)

Introduce students to multiplication through equal groups of a target number, which can be understood as repeated addition. Students can also be introduced to division through the concept of equal sharing. Use of manipulatives at this stage helps students to develop concrete understanding of both concepts.

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