The purpose of this quantitative, quasi-experimental nonequivalent control group design study was to measure the effects of both types of manipulatives on student mathematical understanding of 1st and 4th grade, Title I students. This data is needed for teachers to make informed decisions regarding their instructional choices. 270 participants were separated into three groups based on which type of manipulative their classroom teacher used during instruction: physical, virtual, or both. After 10 weeks of instruction with these manipulatives, student achievement was calculated for each student utilizing the Universal Screeners for Number Sense, and the groups within each grade level band were compared using an analysis of covariance test while controlling for pre-test scores. Both grade levels resulted in statistically significant differences between treatment groups. Physical manipulatives were found to be most impactful for both grade levels, followed by mixed manipulatives, with students using virtual manipulative performing at the lowest levels in both grade levels. It is recommended that future studies consider researching the impact of physical manipulatives first and then virtual manipulatives, repeating this study with a different instrument and/or a longer study period, providing coaching support as part of the study, or researching the impact of an innovative technological tool, such as augmented reality. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]