Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 123 · 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? True or false: the same cotton bud is the one thing we change. (a) True (b) False
2. 2.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
3. 3.⚖️ 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 keep it the same (c) we change it
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 iron setting (b) the same paper (c) the ironing time (d) the kind of juice
5. 5.⚖️ 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
6. 6.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
7. 7.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a magnet (d) a battery cell
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) a cotton bud (d) lemon juice
11. 11.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
12. 12.True or false: writing the message is a job for an adult. (a) True (b) False
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
14. 14.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) letting the paper dry
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) turmeric powder (d) a balloon
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) a cotton bud (d) lemon juice
17. 17.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
19. 19.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
21. 21.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
22. 22.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
23. 23.⚖️ 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
24. 24.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
25. 25.True or false: white paper is needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a balloon (d) white paper
27. 27.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a mirror (d) an adult with an iron
28. 28.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
29. 29.🛟 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
30. 30.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
31. 31.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
32. 32.True or false: yeast is needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
34. 34.⚖️ 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) True (b) False
35. 35.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a mirror (d) lemon juice
37. 37.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) writing the message (d) plugging in the iron
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) a battery cell
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 change it (b) we measure it (c) we keep it the same

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