This experiment will test the following hypothesis: Children's flexible attention to magnitudes (FAM) ability is malleable and can be developed through innovative interventions. The experiment will include a clinical trial to assess the feasibility of a future clinical intervention to improve children's FAM ability for children at-risk for math difficulties.

Participants. Using results from recent number book interventions (ηp2 = .094; Gibson, Gunderson, \& Levine, under review), an estimated sample size of 116 preschool-aged children (3 - 5 years old), or 29 children per group, will be recruited. An additional 8 participants will be recruited to account for any possible attrition during the course of the experiment.

Method and Analyses. Children will be randomly assigned to one of 4 conditions: Size to Number condition, Mixed condition, or one of two control conditions - a Traditional Counting condition or an Non-Numerical Control condition. In each condition, children will complete a pre-test, followed by three intervention sessions with an experimenter, then a post-test. All assessments and intervention sessions will be completed in a one-on-one setting with an experimenter in a quiet area of the child's childcare center or school. Each condition will involve playing a game on a tablet with an experimenter, and the premise of each game will be children going to the zoo. All stimuli for conditions will be created by the University of Dayton computer engineering students in their research and design course. The stimuli for the Size to Number and Mixed conditions will be identical where all trials are incongruent with respect to numerical and spatial magnitudes across sets, but the ordering of instructions and item presentation will differ. In the Size to Number condition, children will view two sets of animals, each enclosed by a box, and will be asked to indicate which set has bigger animals. Children will then switch to a condition in which they are asked to switch and indicate which set has more animals, with 10 trials for both the number and size conditions. Children will receive feedback on each trial. In the Mixed condition, children will receive 20 trials in which size and number trials are intermixed. In the Traditional Counting condition, children will only see congruent numerical and spatial magnitudes, in other words, sets where the object set with more items will also have larger items and the set with fewer items will also have smaller items. Children will be asked to compare these sets, and feedback will be given. Finally, in the Non-Numerical Control condition, children will see various animals on each trial and will be asked to give the animal's name and sound.

An ANCOVA will be used to analyze participant data, with the 4 conditions as the between-subjects variable, and covariates will include children's pre-test, age, gender, and language. The investigator expects to find that both the Size to Number and Mixed conditions will produce higher FAM post-test scores compared to the Traditional Counting and Non-Numerical Control conditions, but do not have a specific prediction as to whether or not the Size to Number or Mixed conditions will outperform one another. The assessments administered at pre- and post-test will include the FAM task, and the investigator will also explore possible transfer effects to children's executive functioning skills and their number line estimation abilities.