Invisible Ink Experiment Worksheet

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

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