Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 592 · 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? 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
2. 2.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) reading the message (d) ironing the paper
3. 3.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) ironing the paper
4. 4.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 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) a cotton bud (d) turmeric powder
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
8. 8.🍋 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
9. 9.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
10. 10.⚖️ 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) False (b) True
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
12. 12.True or false: plugging in the iron is a job a child can do. (a) False (b) True
13. 13.⚖️ 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
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the ironing time
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) white paper (d) a battery cell
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
18. 18.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
19. 19.⚖️ 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
20. 20.⚖️ 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
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
22. 22.🔮 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
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) a balloon (d) turmeric powder
24. 24.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
25. 25.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) writing the message
26. 26.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
27. 27.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) ironing the paper
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) a cotton bud (d) a small bowl
29. 29.⚖️ 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 change it (c) we measure it
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a cotton bud (d) lemon juice
31. 31.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
33. 33.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
34. 34.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
35. 35.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
36. 36.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a balloon (d) a magnet
37. 37.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
40. 40.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed

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