Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 516 · 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.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) white paper (c) a small bowl (d) lemon juice
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) how dark the writing is (d) the kind of juice
5. 5.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
6. 6.True or false: plugging in the iron is a job a child can do. (a) False (b) True
7. 7.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a mirror (c) lemon juice (d) a cotton bud
10. 10.True or false: cutting the lemon is a job for an adult. (a) False (b) True
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) letting the paper dry
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a cotton bud (d) turmeric powder
13. 13.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
14. 14.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) yeast (c) an adult with an iron (d) a small bowl
16. 16.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
18. 18.⚖️ 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
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) a battery cell
20. 20.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
21. 21.⚖️ 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
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
24. 24.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
25. 25.True or false: ironing the paper is a job for an adult. (a) True (b) False
26. 26.⚖️ 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) how dark the writing is (c) the kind of juice (d) the same paper
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
28. 28.True or false: writing the message is a job for an adult. (a) True (b) False
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a battery cell (d) yeast
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
31. 31.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
32. 32.True or false: putting the iron away is a job a child can do. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
34. 34.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) letting the paper dry
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) reading the message
36. 36.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
38. 38.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
39. 39.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it

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