Math tools can be a valuable resource for developing an understanding of math concepts and for solving problems. Most of the ones below are geared towards elementary math.
"How the AL Abacus Will Help Your Kids Master Elementary Math with ANY Curriculum," a post, including videos, from Kate's Homeschool Math Help
"Using a 100-bead abacus in elementary math," from HomeschoolMath.net
"Model and write numbers using base ten blocks," a video from LearnZillion
Number Pieces is one of The Math Learning Center Free Math Apps. Students can manipulate the virtual blocks.
NCTM Illuminations 5 Frame and NCTM Illuminations 10 Frame (Web apps)
Modeling with 10-Frames | Good To Know | WSKG (YouTube Video)
Learn Your Child's Math With This Ten Frame Printable - Scholasatic
How to Teach Number Bonds? | Maths – No Problem!:
Math Playground - Thinking Blocks (Web apps & videos)
Visualizing Word Problems with Bar Model Diagrams Denise Gaskins, with Maths — No Problem! videos
How to Solve a [Grade 5] Maths Problem Using the Bar Model from Singapore | Maths – No Problem!
Singapore Math: A Visual Approach to Word Problems. Model Drawing in Math in Focus (PDF)
Model-Drawing for Maths [Grades 3-6] - http://www.thesingaporemaths.com/ (slides)