Grade 2 Addition and subtraction within 100: Free Course

About this course

Tens and ones make addition and subtraction easier to explain. This Grade 2 course develops number-line, decomposition and regrouping strategies for calculations within 100. Study the complete public source playlist from Khan Academy in English, with all 32 recordings in the on-site classroom. Original lesson titles, source order and repeated entries are preserved.

Course at a glance

What you’ll learn

• Use tens and ones to explain two-digit calculations.
• Add and subtract with and without regrouping.
• Represent calculations on a number line.
• Solve missing-number and everyday word problems.

Skills you’ll gain

• Place value
• Regrouping
• Number lines
• Word problems

Course Overview

The recordings compare adding one with adding ten, and subtracting ones with subtracting tens. Breaking a number into parts supports mental calculation, while regrouping connects a written method with place value. Number-line examples make changes in quantity visible. Stories about objects, lengths and missing quantities ask learners to decide which operation fits the situation rather than copy a procedure. Skip-counting and repeated-addition recordings remain as supporting practice. The source order mixes strategies and applications, so an adult can pause after an example and ask the learner to represent the same calculation with counters, drawings or a different method.

How to study the course

• Videos 1–8: this part of the source list includes “Fence posts for horses” through “Adding 2-digit numbers without regrouping 1”. State the quantities and conditions before calculating. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.
• Videos 9–16: this part of the source list includes “Understanding place value while subtracting ones” through “Breaking apart 2-digit addition problems”. Keep equivalent expressions or representations connected. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.
• Videos 17–24: this part of the source list includes “Skip counting by 5 example” through “Spots on a die”. Check each operation with a small example before extending it. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.
• Videos 25–32: this part of the source list includes “Fewer word problems” through “Subtracting a 1-digit number with regrouping”. Explain a result in words as well as symbols. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.

Who is this for?

This course suits students, returning learners and anyone strengthening the specific mathematics named in the course. It also provides a recorded reference for revisiting a topic after an earlier lesson or study attempt. Choose examples appropriate to your background and allow time to work through the method instead of judging understanding only by how familiar the terminology sounds.

Before you start

Comfort with the preceding arithmetic or algebra skills is useful. Keep paper, a pencil and a calculator when a lesson uses one. Grade-specific courses assume the learner’s earlier grade-level knowledge.

Put the lessons into practice

Represent a two-digit addition with bundles of ten and loose counters. Solve it again on a number line and explain why the answers agree. Create a subtraction story that requires regrouping, then use addition to check it. Ask the learner to explain the meaning of each number before choosing an operation.

This optional study activity is provided by WikiFree for independent practice. Keep your working notes and use the relevant classroom recording to check a step, definition or interpretation. It is not an instructor-marked assignment.

Certificate / Assessment

Watching the public videos and using WikiFree completion tracking does not award a certificate, academic credit, an examination voucher or instructor assessment. Use your practice output to review what you can explain and repeat independently. The recorded lessons provide study material; completion tracking records your progress through that material.

Frequently asked questions

Provider: Khan Academy. Videos play from the Khan Academy channel on YouTube.