At the time of this review, there are no available published research studies on Frog Street Infant. Rigorous research is needed in order to establish evidence for positive effects of Frog Street Infant on children's learning outcomes.

Responsive Relationships and Interactions: Frog Street Infant consistently promotes responsive relationships and interactions, which research shows are the foundation for children's Approaches to Learning, Social and Emotional Development, Language and Communication, and Cognition. The curriculum supports teachers in building trusting relationships with infants and engaging in responsive caregiving. For example, many of the Activity Cards provide specific suggestions to make eye contact, provide physical affection, spend time with individual children, and talk with children. It also offers strategies and vignettes to promote sensitive, responsive caregiving. The curriculum provides many opportunities for teachers to initiate joint attention with infants. However, there is minimal guidance for teachers on how to start a back-and-forth exchange based on the child's focus or interest.

Daily Routines as Opportunities for Learning: The curriculum minimally addresses daily caregiving routines, which are a rich opportunity to support infants' development and learning. Welcome to Frog Street Infant emphasizes following children's verbal and non-verbal cues for hunger, rest, or activity, but it lacks guidance on how to establish developmentally appropriate routines for infants. Additionally, there are only a few examples in the entire curriculum on how to extend children's learning during caregiving routines (e.g., talk with children during mealtimes; chants and rhymes during daily routines; tell children what will happen next during transitions). The curriculum does not provide any further guidance on how teachers can extend children's thinking and communication while engaging in caregiving routines, which are a significant portion of the day for infants.

Play and Exploration: The curriculum provides minimal guidance on research-based practices to support infants' play and exploration. Frog Street Infant repeatedly mentions the importance of providing plenty of space for infants to move and practice physical skills. However, it lacks concrete guidance on how to create an indoor and outdoor environment for active physical play and exploration. The Activity Cards offer some opportunities for infants to engage in open-ended exploration (e.g., manipulating play dough, exploring tactile paths), but they also emphasize a fair amount of teacher-directed activities (e.g., showing a child how to drop an object into a small hole and shake it out). As such, the curriculum lacks opportunities for child-initiated play based on children's interests, which research shows contribute to infants' curiosity, creativity, persistence, and engagement.

Language-Rich Environment and Interactions: The curriculum consistently promotes research-based teaching practices to support infants' language and communication, such as using varied types of talk with infants (e.g., using "parent-ese" or child-directed language, modeling full sentences, narrating actions, expanding on what children say) and supporting infants' emergent literacy. For example, the curriculum provides several learning experiences that encourage caregivers to sing songs, say rhymes, and read books with infants. Research demonstrates these actions support infants' emergent literacy skills.

Promoting Emotional, Behavioral, and Cognitive Self-Regulation: The curriculum consistently promotes research-based practices to support infants' emotional and behavioral self-regulation. The curriculum gives guidance on how teachers can use emotional coaching to help infants understand and begin to manage their emotions. Similarly, to facilitate the development of emotional and behavioral self-regulation skills, the curriculum suggests setting up an environment that minimizes overstimulation (e.g., eliminating bright lights and loud noises) and provides strategies for soothing babies in distress.

Facilitating Cognitive Development: The curriculum consistently promotes research-based teaching practices to support infants' cognition. Many Activity Cards provide prompts for teachers to extend infants' learning during play and exploration, such as talking about the sounds different rattles make or comparing the textures of tactile blocks. In addition, the curriculum helps teachers embed math language and concepts throughout learning experiences (e.g., the "Your Hands, My Hands" activity includes prompts to count fingers and compare the size of hands). Finally, the curriculum provides guidance on how to scaffold infants' problem-solving skills.

Supporting Physical Development: The curriculum consistently promotes research-based practices to support infants' perceptual, motor, and physical development. For example, the Activity Cards provide learning experiences to support infants' gross and fine motor skills (e.g., positioning the infant in a prone position to play; encouraging the infant to reach and grasp). Similarly, the Activity Cards suggest intentional teaching practices to support perceptual understanding and perceptual-motor development (e.g., playing games about body parts, teaching movement words). The curriculum includes many varied opportunities for infants to practice new physical skills, such as squeezing a sensory glove, a sponge, or squeeze toys (e.g., a baster or an eyedropper).

Scope: The curriculum clearly identifies five developmental domains: Language Development, Cognitive Development, Social and Emotional Development, Physical Development, and Approaches Toward Learning. Welcome to Frog Street Infant provides information on each of these learning domains, and the Activity Cards provide learning experiences to support children's development in each of these areas.

Sequence: The curriculum provides Activity Cards for Physical, Social Emotional, Language, and Cognitive Development. The activities are organized by age: 0–3 months, 3–6 months, 6–12 months, and 12–18 months. These Activity Cards provide sequences of learning experiences that are based on children's developmental progressions with multiple, related opportunities for children to explore or learn concepts or skills in each domain. Welcome to Frog Street Infant describes how teachers use the Activity Cards to make an individualized weekly plan for each child.

Alignment with the ELOF: A thorough review of all the curriculum materials indicates Frog Street Infant is mostly aligned with the Head Start Early Learning Outcomes Framework (ELOF) domains and sub-domains. The learning experiences described in the Activity Cards support children across the majority of ELOF sub-domains. The curriculum partially addresses a few ELOF sub-domains: Creativity; Imitation and Symbolic Representation and Play; and Health, Safety, and Nutrition.

Learning Goals: The curriculum provides Frog Street Infant Learning Goals, which are measurable and developmentally appropriate. The learning goals are referenced throughout the Activity Cards, and the learning experiences support the stated goals. The curriculum acknowledges infants are at many different stages of development and that some infants may develop faster or slower in a particular domain. However, the curriculum lacks explicit guidance on how to use the learning goals with diverse children or how to modify learning goals for activities to individualize learning experiences for all children.

Ongoing Observation and Documentation: Welcome to Frog Street Infant describes how ongoing assessment is a process of observing and documenting children's development for the purposes of planning activities to support the growth and development of an individual infant. It includes brief descriptions of written observations, anecdotal records, and work samples. The Planning and Assessment CD provides forms for written observations and anecdotal records. However, the curriculum does not provide specific guidance embedded throughout curriculum materials on how teachers can engage in this process.

Standardized and Structured Assessment Instruments: The curriculum describes and provides a structured assessment tool, the Frog Street Infant Developmental Checklist, that aligns with the curriculum's learning goals. However, the curriculum lacks guidance on how to choose a standardized and structured assessment instrument that is valid, reliable, and individually, culturally, and linguistically appropriate.

Communicating with Families: Welcome to Frog Street Infant provides some guidance on how to communicate with families (e.g., the parent bulletin board, sending home letters), but most of the suggested strategies describe unidirectional communication (from program to family). The Planning and Assessment CD provides materials to use to communicate with families, including an Infant Daily Report Form and 24 Parent Letters. All forms for communicating with families are translated into Spanish, but there is no further guidance on how to communicate with families from diverse cultures or who speak home languages other than English.

Engaging Families: Welcome to Frog Street Infant provides some guidance on how to engage families in the program (e.g., invitations to staff training; encouraging use of the school resource library). The 24 Parent Letters provide specific tips for "What You Can Do" at home to extend children's development and learning (e.g., read to children daily as part of their bedtime routine; provide a variety of rattles and musical toys for children to explore cause and effect). The Parent Letters are translated into Spanish, but there is no guidance on how to engage families who speak languages other than English and Spanish, are from diverse cultures, or who have disabilities or other special needs.

Professional Development: Frog Street offers a range of in-person courses, including both initial (Frog Street Infant Curriculum Implementation) and ongoing (Frog Street Infant Curriculum Follow-Up) training sessions. Additional courses cover a wide range of content, such as family engagement and how to plan age-appropriate activities in each domain. The curriculum also offers professional learning webinars that can be customized to meet the needs of programs using a pre-webinar questionnaire to identify challenges and share successes.

Curriculum Materials to Support Implementation: The curriculum includes a comprehensive set of materials to support implementation. Both Welcome to Frog Street Infant and an introductory video in the online portal provide an overview of the curriculum materials, such as Activity Cards, CDs, manipulatives, and books for children. The curriculum features 264 Activity Cards organized by domain and age, which provide best practices, information on child development, learning objectives, required materials, and activity instructions. The curriculum also provides an Infant Activity Tracker to help teachers organize which activities they will focus on for each child.

• Fidelity Tool: The curriculum offers the Frog Street Infant Administrator Classroom Observation Tool, which can be used to assess fidelity of implementation. Program administrators or coaches can use the tool to assess infant teachers' sensitivity to social and emotional needs of children, instructional strategies, classroom environment, and intentionality.

Active Exploration: Welcome to Frog Street Infant discusses how infants need space and opportunities to move freely. Some of the Activity Cards allow children to actively explore their environment, such as manipulating play dough and touching or crawling on a tactile path. However, many of the activities are more teacher-directed, inviting infants to do something very specific and leaving less opportunity for them to engage with the environment in open-ended ways. For example, one activity instructs teachers to put blue and yellow paint on children's hands to make green. In another activity, teachers model how to create art with a golf ball in a pan, and children are directed to do the same thing.

Interactions That Extend Children's Learning: Some Activity Cards provide supports for teachers to engage in interactions that extend infants' exploration, thinking, and communication. For example, teachers introduce two rattles and talk about the different sounds with infants. Another activity encourages children to stack tactile blocks and prompts teachers to compare the textures using descriptive words. However, some guidance in the Activity Cards would limit children's open-ended exploration and communication. For example, an activity invites a child to explore a musical toy, but encourages teachers to demonstrate the "right buttons to push." Another activity tells teachers to stack three blocks, encourage the child to copy the tower, repeat, and count the blocks in the towers with the child. This type of guidance for how the teacher should interact with the child during block play limits what the child may learn from exploring the blocks in a more open-ended way with suggested prompts for teachers that focus more on the child's exploration (e.g., balance, size, quantity, symbolic representation).

Individualization: The curriculum provides minimal guidance on how to individualize learning experiences for all children. The Activity Cards are translated into Spanish, but there is no guidance on how and when to use the Spanish translations with children who are dual language learners (DLLs). Welcome to Frog Street Infant offers a few general tips for working with children with specific needs (e.g., visual and hearing challenges, physical delays). The curriculum does not address how to individualize learning experiences for children from diverse cultures, children who speak languages other than English and Spanish, or how to modify the activities for children with other types of disabilities, suspected delays, or other special needs.

Environment: Welcome to Frog Street Infant offers limited guidance on designing the indoor and outdoor environment. It focuses primarily on keeping the environment physically safe and free from overstimulation (e.g., bright lights, loud noises, too many choices). The curriculum also emphasizes the importance of giving children space to freely move. However, there is no comprehensive or specific guidance on how to design a well-organized environment to support children's active exploration or development in the ELOF domains.

Learning Materials: Welcome to Frog Street Infant and many Activity Cards offer examples of materials that could support open-ended exploration and inquiry (e.g., rattles, blocks, nesting toys, sight and sound tubes, scarves). Similarly, the curriculum package comes with some manipulatives that may be used for open-ended exploration and inquiry (e.g., balls, musical instruments, a mirror). The curriculum provides a few suggested materials for children with specific disabilities (e.g., simple adaptive devices to help older infants with delayed motor development turn book pages). However, the curriculum lacks guidance on how to select learning materials that authentically represent the cultures, ethnicities, and home languages of children in the program.

Schedule and Routines: Welcome to Frog Street Infant mentions the importance of following children's cues rather than using a pre-determined schedule. It provides examples of verbal and non-verbal cues children may express when they are ready for activity, need a rest, or are hungry or sleepy. However, the curriculum does not adequately discuss how teachers can build their schedule flexibly around children's routines, nor does it discuss how to effectively support children's development and learning during caregiving routines.

Interactions: Welcome to Frog Street Infant includes a brief section on "Cultural Sensitivity," with very few tips that could be used to build relationships with children and families from diverse cultural backgrounds (e.g., treating people as individuals rather than stereotypes; modeling respect for others). However, there is no guidance on learning how families interact with their child or how to use this information to engage in culturally responsive interactions.

Learning Experiences: The curriculum lacks guidance on how to engage infants and toddlers in caregiving routines and learning experiences that build on families' traditions, cultures, values, and beliefs.

Learning Environment: In order to provide learning materials that reflect children and families from diverse cultures and ethnicities, the curriculum suggests presenting a variety of foods and using books, photographs, and posters that celebrate a wide variety of ethnic groups. Additionally, the curriculum's Literature Library includes books with photos of children and families from diverse cultures and ethnicities. However, the curriculum lacks any guidance on how to select and use learning materials that authentically represent the cultures and ethnicities of children and families in the program.

Linguistic Responsiveness: The curriculum offers many materials in English and Spanish (e.g., Activity Cards, vocabulary, children's books), but the curriculum does not include any guidance on how or when teachers should use the English or Spanish versions. Welcome to Frog Street Infant describes how learning a second language can be beneficial for all children, with some general scaffolding strategies for children who are DLLs (e.g., keeping language simple, using actions and illustrations, using visual aids). However, the curriculum lacks guidance on how teachers can partner with families to develop an intentional language plan for children who are DLLs. The curriculum also does not address research-based strategies for linguistic responsiveness, such as encouraging teachers to communicate in their own strongest language(s) or using some words and phrases in children's home languages.

Teaching Practices and Interventions: Welcome to Frog Street Infant includes general strategies to support children with visual challenges, hearing challenges, and delayed motor development. Some of these strategies are research-based teaching practices, such as inviting a child to participate partially if a complete activity is too challenging, or using visual representations to teach new concepts. However, these teaching practices and interventions are not embedded throughout the Activity Cards, and they are limited to only three kinds of disabilities. Therefore, they lack the comprehensive support a teacher needs to provide routines and learning experiences that are fully accessible to a child with a disability, suspected delay, or special need.

Learning Environment: Welcome to Frog Street Infant offers few strategies to ensure the environment and materials are accessible for children with visual challenges, hearing challenges, and delayed motor development. Suggested strategies include seating a child to optimize vision (e.g., consider lighting and glare); using line drawings with minimal background clutter; providing simple adaptive devices; and changing a child's position. However, the curriculum lacks overall guidance on how to ensure the physical environment and learning materials are accessible to all children, nor does it include any specific examples to support children with a wider range of disabilities, suspected delays, or other special needs.

Individualization Based on Interests: The curriculum does not address how to plan learning experiences that build on individual children's interests. Learning experiences are pre-planned, and there is no guidance on how to modify them based on the interests of individual children in the program.

Individualization Based on Strengths and Needs: The Activity Cards are designed to be chosen and used based on individual children's developmental levels. Teachers choose one activity for each domain for each child. These activities should be chosen based on the teachers' understanding of each child's development, and the activities should be repeated throughout the week. Beyond this general overview, there is no guidance on how teachers can select activities based on individual children's strengths and needs.