Tennis Data Lab: Practice Companion

What you will make

A synthetic tennis practice journal and strategy board

• Model a small practice record and validate its boundaries.
• Calculate an aggregate rate with the correct denominator.
• Translate pointer coordinates into a court direction diagram.
• Save synthetic journals and review an AI observation against measured facts.

Settle in together

Laptop or desktop with a modern browser for editing. Phones can read the guide and observe or try the preview. Start with fictional data.

Allow about 5 minutes to get ready. Six missions in order. Try one or two 5–12 minute activities, take a break, and resume at the next activity. Plan several short sittings per mission; the full 75–90 minute lesson remains the detailed reference. End each sitting with a saved copy and one sentence: next time we will… Times are estimates awaiting family pilots.

• For ages 9–12, work beside a parent on a computer with a keyboard. A phone can read the guide and watch; use a computer for editing. Older learners may try the full lesson's stretch task after the core checks.
• Open the first mission's browser workspace and press Run before installing anything. No payment, child account, or AI key is needed for that introduction. If the runtime reports unavailable, keep your files, read its error, and use the course-specific fallback below with adult help.
• The starter validates only a nonempty goal, summarizes the record count, draws an endpoint dot and does not save yet. Missions add validation, arithmetic, arrows and storage in order. This is a software project using fictional counts, not advice about real athlete ability or health.
• Parent-guided same-version local handoff: keep the current workspace tab open and record one exact edited line/value from File index.html (such as your changed heading or installed validateRecord). Use Export backup, then the trusted parent-page Download index.html. Keep both downloads; JSON is a backup, not an executable app. Download /lab-starters/tennis-apps.zip, extract a fresh tennis-apps folder, and replace only its root index.html with the downloaded current source. Confirm its actual name is index.html, not index.html.txt, and open it as plain text to find the recorded edited line before claiming local evidence. No packages are needed. Open the replaced file in a separate LOCAL app tab and check the known source edit and its expected behavior. Recreate the same fictional practice cards there: workspace appStorage does not automatically populate local app memory, and the court/shot text must be re-entered too. Open DevTools Console for the LOCAL app tab, not the guardian page or opaque preview. If file-origin storage is blocked, a parent runs python3 -m http.server 8080 --bind 127.0.0.1 from that extracted folder and opens http://127.0.0.1:8080/index.html; re-enter the cards because this is another origin. Keep the workspace/JSON backup if a browser or storage check fails and mark it pending or failed. A pristine download is baseline evidence only; repeat transfer/verification after code edits.
• Full lessons provide whole named-function replacements; keep the form and pointer event handlers. Local Console/storage checks use the transferred current source and recreated fictional cards.
• Keep two practice cards: A goal Aim toward center, attempts 10, hits 4, reflection Try another fictional set; B goal Repeat center target, attempts 20, hits 18, reflection The second fictional drill used a closer target. Their different conditions do not prove improvement. Record storage later saves journals only; court arrows and shot text are temporary.
• Keep the original starter unchanged as a reference. Export a working copy before a risky edit or reset. Work and the optional progress checklist stay on this device; an export is your portable backup. A checked box records your own report, not a verified assessment.
• Use invented names, notes and records. The parent handles accounts, optional AI and sharing. Predict together, let the child make one choice, change one thing, test it, then explain what happened. An assistant is optional; the supplied code and a partner work too.