Grade 1 Addition and subtraction: Free Course

About this course

Mental arithmetic grows from number relationships. This Grade 1 course develops making-ten strategies, decomposition, place-value reasoning and the connection between addition and subtraction. Study the complete public source playlist from Khan Academy in English, with all 18 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 making-ten and decomposition strategies.
• Add ones and tens with place-value understanding.
• Relate addition to subtraction.
• Solve comparison stories and interpret the equal sign.

Skills you’ll gain

• Making ten
• Mental arithmetic
• Place-value addition
• Equality

Course Overview

Examples such as adding eight and seven show how a known total of ten can simplify a calculation. Two-digit recordings connect adding ones with adding tens, including regrouping in a one-digit addition. Three-addend examples encourage flexible grouping. Comparison stories require distinguishing how many in all from how many more, and the equal-sign lesson emphasizes that both sides represent the same value. The source includes several representations of these ideas, all retained in order. Ask learners to explain why a strategy preserves the total and to compare two methods when a calculation can be solved in more than one way.

How to study the course

• Videos 1–4: this part of the source list includes “Comparison word problems: roly-polies” through “Adding 8 + 7”. 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 5–9: this part of the source list includes “Understanding place value while adding tens” through “Adding two-digit numbers without regrouping”. 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 10–13: this part of the source list includes “Exercising gorillas” through “Adding 7 + 6”. 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 14–18: this part of the source list includes “Sea monsters and superheroes” through “Relating addition and subtraction”. 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

Solve a sum such as eight plus seven by making ten, then show a different decomposition. Explain why both methods give the same total. Create a comparison story with two groups and write a related addition and subtraction sentence. Include an equation with expressions on both sides to check understanding of equality.

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.