Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 104 · 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.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) cutting the lemon
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
3. 3.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
4. 4.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
6. 6.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
7. 7.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
8. 8.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
9. 9.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
11. 11.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
12. 12.True or false: putting the iron away is a job for an adult. (a) True (b) False
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the same paper (d) how dark the writing is
14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
16. 16.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
17. 17.True or false: plugging in the iron is a job for an adult. (a) True (b) False
18. 18.True or false: reading the message is a job for an adult. (a) True (b) False
19. 19.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
22. 22.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
23. 23.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
24. 24.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
28. 28.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
29. 29.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
30. 30.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) white paper (d) a small bowl
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) the same paper (d) how dark the writing is
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) yeast (d) a magnet
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a cotton bud (d) lemon juice
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) an adult with an iron (d) a small bowl
36. 36.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
37. 37.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
38. 38.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ 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) how dark the writing is (c) the iron setting
40. 40.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud

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