### Introduction

### Research Methods

### Subjects

### Tools

#### Experimental design

#### Program design

*Rosa hybrida (*32 times),

*Helianthus annuus*L. (23 times),

*Chrysanthemum morifolium*(20 times),

*Cosmos bipinnatus*Cav. (14 times),

*Dianthus caryophyllus*L. (seven times),

*Hedera helix*(four times), and among 19 species of fruit trees, we used

*Citrus limon*(seven times). The details of the 10 sessions of the horticulture-mathematics integration program are as follows.

*Cornus sericea*‘Flaviramea’ and arrange flowers in order to understand the number of edges and faces as well as shapes, after which they put them in bottles and made herbariums. Session 4 is Unit 4, Cuboids and Cubes, in which students were to determine the faces of cubes by equally arranging six flowers of

*Rosa hybrida*(Miniature Roses) each on six cube floral foams in the size of 5×5×5 cm and creating a topiary, thereby learning that the faces have the same shape. Session 5 is Unit 5, Patterns and Correspondence (1), in which students were to understand correspondence and patterns by examining the 1:5 correspondence pattern with five leaves divided in one stem of

*Pachira aquatica*to determine 1:1 correspondence of plant and flowerpot. Session 6 is Unit 6, Day Planning, in which students were to determine the daily rules according to time flow by creating a 20cm-diameter wreath by expressing their daily routines with

*Gossypium hirsutum*, dried lemons, fake applies and pine cones. Session 7 is Unit 7, Basics of Fractions, in which students equally divided the whole cylindrical container into three parts to understand fractions, put two types of colored stones up to 2/3 of the container and planted

*Tillandsia Ionantha*. Session 8 is Unit 8, Basics of Division, in which students divided soap base provided to two students into an equal number of pieces, added color with paprika and sweet pumpkin powder, and made persimmon-shaped soap. Session 9 is Unit 9, Capacity (mL), in which students made tumblers decorated in pressed flowers to test capacity and find out the relationship between L and mL, poured 1 L of water into a 400 mL tumbler, and learned the relationship of capacity. Session 10 is Unit 10, Line Graph, in which students were to learn the order of drawing a line graph by planting

*Hedera helix*and inducing stems on the structure, after which they learned how to measure the longest and the second-longest stem with a ruler and draw them on the graph. They measured the lengths once a week and recorded their growth to understand the line graph. Moreover, the program to develop money calculating ability is Unit 11, Using Currency (1), (2), in which students in Sessions 1–2 identified the face value of bills and coins and then were to purchase two materials. In Sessions 3–5, Calculating the Prices, students were to find money and purchase 3 different materials in the same price, a couple of thousands of won, in Sessions 3–4, and calculate the amount that added the prices of two materials and purchase the materials in the relevant amount. In Sessions 6–7, Calculating the Change, students calculated the change after buying things within 5,000 won. In Sessions 8–10, Purchasing Items, students were to purchase materials within 10,000 won. The program was designed so that there is no rounding up of the sum when purchasing two or more items (Table 1, Fig. 1).

#### Program implementation

^{2}where there were two 180 × 140 cm tables with six students sitting in each. The program was carried out by one main therapist with a Horticultural Therapist Registered-Grade II certificate (certified by Korean Horticultural Therapy Association) and assistant therapists-one special education teacher with 10 years of experience and one floral designer with a Craftsman Floral Design certificate. The experimental group with 12 students participated in the 10-session program once a week for 60 minutes each during spare time in the evening living in the dorms after school. The horticulture-mathematics integration program was comprised of 10 minutes of introduction, 40 minutes of development, and 10 minutes of wrap-up. There was some relationship building time to motivate the students in the introduction stage, and learning objectives were provided to promote understanding. Photographs related to class were presented on PowerPoint to arouse their interest, and the works they will be making were introduced in real objects. In the development stage, students were to purchase horticultural materials as the first activity for exploration of problems and experiences, and to carry out the horticulture-mathematics integ ration p rog ram as the s econd activity. The s tudents asking for h elp were g iven t he l east bit of h elp to promote sense of achievement in completing their works in the development s tag e, helping them complete them in time. In the wrap-up stage, the students introduced their works, shared their thoughts, and briefly talked about mathematical contents to check their l earning objectives. Works to make in the following sessions were introduced in real objects to arouse their interest in the next class.

### Assessment tools and analysis method

#### Assessment tools

### (1) Mathematical attitude test

*α*of the test was .94, showing high reliability.

### (2) Money calculating ability test

#### Analysis method

*p*< .05.

### Results and Discussion

### Preliminary test of homogeneity between groups

*p*= .272), attitude toward the subject (

*p*= .839), and study habit related to the subject (

*p*= .885). Money calculating ability also did not show a significant difference in all items such as knowing the amount of money (

*p*= .321), calculating the price of goods (

*p*= .884), and calculating change (

*p*= .771), indicating that the two groups were homogeneous and thus this study could be conducted.

### Pretest and posttest within group

#### Change in mathematical attitude

*(p*= .340), attitude toward the subject (

*p*= .236), and study habit related to the subject (

*p*= 1.000). The experimental group showed a statistically significant difference in all of self-concept about the subject (

*p*= .003), attitude toward the subject (

*p*= .004), and study habit related to the subject (

*p*= .012; Table 3). In other words, applying the horticulture-mathematics integration program had a positive effect on mathematical attitude of students. This result is similar to the study that implemented the horticulture-mathematics integration program for 12 sessions in math class of Grade 4 students in elementary school and found out that the program helped students find interest in mathematics, thereby increasing the fun of studying mathematics (Kim et al., 2014). This is also supported by the study that mathematical activities through nature form positive attitudes toward mathematics by arousing curiosity and sense of closeness for preschool children (Charlesworth, 2005). This study gave a sense of closeness to students using plants as the main ingredient, and various horticultural activities were used as the learning materials with mathematical contents. However, concrete objects such as horticultural materials and relatively simple activities brought curiosity, pleasure and patience rather than fear of tasks for students with intellectual disabilities that have difficulty in abstract thinking, thereby showing enthusiastic participation (Choi and Lee, 2000). Furthermore, the outcomes also gave them a sense of achievement and confidence, showing that positive mathematical experience with increasing positive emotions may have also affected mathematical attitude (Joo et al. 2012; Sagong, 2017).

#### Pretest-posttest change in money calculating ability

*p*= .046) and experimental group (

*p*= .020). Calculating the price of goods also showed a significant difference in the control group (

*p*= .023) and experimental group (

*p*= .018), and calculating change in the control group (

*p*= .008) and experimental group (

*p*= .007; Table 4). Even though the experimental group showed a statistically significant change, the control group also showed a statistically significant change and thus could not prove the effect on improvement of money calculating ability. However, the pretest-posttest difference in mean scores of each item showed that knowing the amount of money increased by 3.3 points in the control group and 24.1 points in the experimental group; calculating the price of goods increased by 6.7 points in the control group and 15.0 points in the experimental group; and calculating change increased by 5.8 points in the control group and 18.3 points in the experimental group. The experimental group showed an increase of at least 15.0 points in all items, proving that the program had a positive effect on increasing money calculating ability compared to the control group. This is because the program was short with just 10 sessions and had little chance to repeat, and there was not enough time to carry out two activities in the 60-minute session, but students participated enthusiastically in purchasing materials with high interest in horticultural activities. In addition, repeating the activity to find money according to the amount and make payment for purchase resulted in great improvement in all items. This is similar to the result by Lee and Kang (2014) proving in a simulation that purchasing objects on flyers using replica money was effective in improving money calculating ability. Even though it was a simulation, this program has significance in providing guidance for participants to experience mathematical problem solving in the real-life scene of purchasing horticultural materials (Moon and Jeon, 2020).

### Conclusion

*p*= .003), attitude toward the subject (

*p*= .004), and study habit related to the subject (

*p*= .012). Abstractness among the characteristics of mathematics is also referred to as the power to think and can be obtained from specific experience. Therefore, the basic mathematics curriculum must help students learn abstractness through the activities of sufficiently manipulating various concrete materials (Lee, 2013; MOE, 2018). Moreover, enabling students to experience the mathematical concepts in five senses and share emotional communion helps them more easily and conveniently accept mathematics (Lee, 2013). Horticultural activities require direct manipulation using concrete objects mediated by plants, stimulating five senses and enabling the plant as a living organism to share emotional communion with the subject. Accordingly, these activities are necessary for students with intellectual disabilities to understand mathematics. High school also requires students to learn the basic concepts of mathematics and develop desirable learning attitudes toward mathematics with communication activities by mathematically exploring and manipulating objects in everyday life (MOE, 2018). Accordingly, this program is suitable for developing an understanding of mathematical concepts and cultivating positive mathematical attitude by integrating mathematics with plant and horticultural activities that are familiar to students with intellectual disabilities. Plants and horticultural activities increased curiosity, interest and attention with splendid colors and diverse forms of plants as well as enthusiastic participation within fear of tasks, thereby showing longer attention span as the sessions went on (Choi and Lee, 2000). Experiencing and manipulating concrete objects like plants and horticultural materials provided multisensory stimulations and affected conceptualization (Choi and Lee, 2000), memory and understanding of mathematical concepts, which increased students answering more enthusiastically and accurately to questions about the concepts learned before the wrap-up stage and the next session. The natural experience of positive mathematical learning such as curiosity, interest, attention and joy in class brought positive changes to mathematical attitude. Moreover, money calculating ability showed a significant difference in all three items for both the control group and experimental group, thereby failing to prove the effect on the increase of money calculating ability. However, according to Moon and Jeon (2020), the internet and home-study materials are used in mathematics classes for students with intellectual disabilities. But since students tend to show difficulty in generalizing the learning contents (Shin, 2017), it is necessary to develop a program to provide real-life scenes at school that can be experienced in the community and guidance to actively solve mathematical problems when required. Therefore, purchasing horticultural materials in the horticulture-mathematics integration program is a highly appropriate attempt at education as students with intellectual disabilities can learn and use money based on active experience of actually purchasing items necessary for the program using real-life materials (Lee and Paik, 2004; Moon and Jeon, 2020).