Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 424 · 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 a child can do? (a) ironing the paper (b) reading the message (c) putting the iron away (d) cutting the lemon
2. 2.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) letting the paper dry
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) an adult with an iron (d) a small bowl
4. 4.⚖️ 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 ironing time (c) how dark the writing is
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
6. 6.⚖️ 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
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
9. 9.True or false: writing the message is a job for an adult. (a) True (b) False
10. 10.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a mirror (d) a magnet
13. 13.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
14. 14.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
15. 15.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) lemon juice (d) a mirror
20. 20.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a balloon (d) lemon juice
21. 21.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) reading the message (d) dipping the cotton bud
22. 22.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
24. 24.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) yeast (d) turmeric powder
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud (d) the same paper
26. 26.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) the iron is brown (d) heat adds colour
27. 27.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
28. 28.⚖️ 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 kind of juice (c) the iron setting
29. 29.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
30. 30.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
31. 31.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
33. 33.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
34. 34.⚖️ 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
35. 35.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a magnet (d) a small bowl
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) lemon juice (d) a small bowl
37. 37.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
39. 39.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
40. 40.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False

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