This lesson consists of showing you how to use the Sieve of Eratosthenes to find all prime numbers below a certain value. In this case, below 100. (05:50)

In this video, Mr. Almeida explains how to use mental strategies to add and subtract within 20 using the relationship between addition and subtraction. This is one of the strategies suggested in the Common Core State Standards for Mathematics, 1.OA.6... and 2.OA.2. This would be a great resource for teacher professional development or for direction instruction. (04:22)[more]

En este video, el profesor habla sobre varias operaciones básicas. Empieza con el valor absoluto y sigue con la suma de enteros, resta de enteros, multiplicación de enteros, y la división de enteros. El video ofrece ejemplos de cada operacion. (10:17...)[more]

In this video, Mr. Almeida explains how to use mental strategies to add within 20 using the "make 10" strategy. This is one of the strategies suggested in the Common Core State Standards for Mathematics, 1.OA.6 and 2.OA.2. With practice, this strateg...y can help students gain fluency when adding within 20. Eventually students will memorize these facts, which is expected by the end of grade 2. This would be a great resource for teacher professional development or for direct instruction. (5:48)[more]

This is an introduction to basic word problem terms. Larry discusses key words that are usually associated with a particular mathematical operation. Terms are shown for addition, subtraction, multiplication, and division. (02:37)

This lesson works through typical operations done on numbers: absolute value, grouping, opposites, addition, subtraction, multiplication, division and simple exponents. (30:36)

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