Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 127 · 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.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
3. 3.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
4. 4.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) cutting the lemon
5. 5.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
6. 6.True or false: plugging in the iron is a job for an adult. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
8. 8.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same paper (c) the kind of juice (d) how dark the writing is
10. 10.True or false: cutting the lemon is a job a child can do. (a) True (b) False
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a magnet
12. 12.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
13. 13.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) turmeric powder (d) a balloon
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) white paper (d) a small bowl
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
16. 16.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
17. 17.⚖️ 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 keep it the same (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.🍋 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
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) white paper (d) yeast
24. 24.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
25. 25.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
26. 26.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a magnet (d) yeast
28. 28.True or false: putting the iron away is a job a child can do. (a) False (b) True
29. 29.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) putting the iron away
31. 31.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) white paper
33. 33.⚖️ 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
34. 34.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
35. 35.True or false: letting the paper dry is a job a child can do. (a) False (b) True
36. 36.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
38. 38.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
39. 39.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
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 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