Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 200 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
4. 4.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) writing the message
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a balloon
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
8. 8.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
9. 9.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a cotton bud (d) turmeric powder
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) the ironing time (d) how dark the writing is
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
14. 14.True or false: ironing the paper is a job for an adult. (a) False (b) True
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
16. 16.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a mirror (d) white paper
17. 17.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) a cotton bud
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
20. 20.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
23. 23.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
24. 24.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) white paper (d) a small bowl
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the iron setting (d) the same paper
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a mirror (c) lemon juice (d) a cotton bud
30. 30.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
34. 34.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) ironing the paper (d) dipping the cotton bud
35. 35.True or false: letting the paper dry is a job for an adult. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
37. 37.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a mirror (d) lemon juice
38. 38.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids